diff --git a/admin/auth.php b/admin/auth.php
index f501ed7c07acd..a5a88a9d9b2be 100644
--- a/admin/auth.php
+++ b/admin/auth.php
@@ -28,7 +28,7 @@
 }
 
 if (!empty($auth) and !exists_auth_plugin($auth)) {
-    print_error('pluginnotinstalled', 'auth', $returnurl, $auth);
+    throw new \moodle_exception('pluginnotinstalled', 'auth', $returnurl, $auth);
 }
 
 ////////////////////////////////////////////////////////////////////////////////
@@ -55,7 +55,7 @@
         $key = array_search($auth, $authsenabled);
         // check auth plugin is valid
         if ($key === false) {
-            print_error('pluginnotenabled', 'auth', $returnurl, $auth);
+            throw new \moodle_exception('pluginnotenabled', 'auth', $returnurl, $auth);
         }
         // move down the list
         if ($key < (count($authsenabled) - 1)) {
@@ -72,7 +72,7 @@
         $key = array_search($auth, $authsenabled);
         // check auth is valid
         if ($key === false) {
-            print_error('pluginnotenabled', 'auth', $returnurl, $auth);
+            throw new \moodle_exception('pluginnotenabled', 'auth', $returnurl, $auth);
         }
         // move up the list
         if ($key >= 1) {
diff --git a/admin/blocks.php b/admin/blocks.php
index 00132cc855b35..19f5829a704e5 100644
--- a/admin/blocks.php
+++ b/admin/blocks.php
@@ -75,7 +75,7 @@
 /// Get and sort the existing blocks
 
     if (!$blocks = $DB->get_records('block', array(), 'name ASC')) {
-        print_error('noblocks', 'error');  // Should never happen
+        throw new \moodle_exception('noblocks', 'error');  // Should never happen.
     }
 
     $incompatible = array();
diff --git a/admin/category.php b/admin/category.php
index e11507a218a1d..fb37fa1d7e0aa 100644
--- a/admin/category.php
+++ b/admin/category.php
@@ -41,11 +41,11 @@
 $settingspage = $adminroot->locate($category, true);
 
 if (empty($settingspage) or !($settingspage instanceof admin_category)) {
-    print_error('categoryerror', 'admin', "$CFG->wwwroot/$CFG->admin/");
+    throw new \moodle_exception('categoryerror', 'error', "$CFG->wwwroot/$CFG->admin/");
 }
 
 if (!($settingspage->check_access())) {
-    print_error('accessdenied', 'admin');
+    throw new \moodle_exception('accessdenied', 'admin');
 }
 
 $hassiteconfig = has_capability('moodle/site:config', $PAGE->context);
diff --git a/admin/cli/restore_backup.php b/admin/cli/restore_backup.php
index 6f5de424995a6..46eccb2db4fba 100644
--- a/admin/cli/restore_backup.php
+++ b/admin/cli/restore_backup.php
@@ -69,15 +69,15 @@
 }
 
 if (!$admin = get_admin()) {
-    print_error('noadmins');
+    throw new \moodle_exception('noadmins');
 }
 
 if (!file_exists($options['file'])) {
-    print_error('filenotfound');
+    throw new \moodle_exception('filenotfound');
 }
 
 if (!$category = $DB->get_record('course_categories', ['id' => $options['categoryid']], 'id')) {
-    print_error('invalidcategoryid');
+    throw new \moodle_exception('invalidcategoryid');
 }
 
 $backupdir = "restore_" . uniqid();
@@ -102,7 +102,7 @@
 } catch (Exception $e) {
     cli_heading(get_string('cleaningtempdata'));
     fulldelete($path);
-    print_error('generalexceptionmessage', 'error', '', $e->getMessage());
+    throw new \moodle_exception('generalexceptionmessage', 'error', '', $e->getMessage());
 }
 
 cli_heading(get_string('restoredcourseid', 'backup', $courseid));
diff --git a/admin/contentbank.php b/admin/contentbank.php
index 95a7c4328b89c..98514e2204a00 100644
--- a/admin/contentbank.php
+++ b/admin/contentbank.php
@@ -42,7 +42,7 @@
 $sortorder = array_flip(array_keys($plugins));
 
 if (!isset($plugins[$name])) {
-    print_error('contenttypenotfound', 'error', $return, $name);
+    throw new \moodle_exception('contenttypenotfound', 'error', $return, $name);
 }
 
 switch ($action) {
diff --git a/admin/courseformats.php b/admin/courseformats.php
index 6cf30bd753828..95d40b164ba45 100644
--- a/admin/courseformats.php
+++ b/admin/courseformats.php
@@ -41,7 +41,7 @@
 $sortorder = array_flip(array_keys($formatplugins));
 
 if (!isset($formatplugins[$formatname])) {
-    print_error('courseformatnotfound', 'error', $return, $formatname);
+    throw new \moodle_exception('courseformatnotfound', 'error', $return, $formatname);
 }
 
 switch ($action) {
diff --git a/admin/cron.php b/admin/cron.php
index ed19d46360e8b..df009e255b296 100644
--- a/admin/cron.php
+++ b/admin/cron.php
@@ -58,7 +58,7 @@
 // check if execution allowed
 if (!empty($CFG->cronclionly)) {
     // This script can only be run via the cli.
-    print_error('cronerrorclionly', 'admin');
+    throw new \moodle_exception('cronerrorclionly', 'admin');
     exit;
 }
 // This script is being called via the web, so check the password if there is one.
@@ -66,7 +66,7 @@
     $pass = optional_param('password', '', PARAM_RAW);
     if ($pass != $CFG->cronremotepassword) {
         // wrong password.
-        print_error('cronerrorpassword', 'admin');
+        throw new \moodle_exception('cronerrorpassword', 'admin');
         exit;
     }
 }
diff --git a/admin/customfields.php b/admin/customfields.php
index 38f917a1ccd14..aa80fd9222e54 100644
--- a/admin/customfields.php
+++ b/admin/customfields.php
@@ -41,7 +41,7 @@
 $sortorder = array_flip(array_keys($customfieldplugins));
 
 if (!isset($customfieldplugins[$customfieldname])) {
-    print_error('customfieldnotfound', 'error', $return, $customfieldname);
+    throw new \moodle_exception('customfieldnotfound', 'error', $return, $customfieldname);
 }
 
 switch ($action) {
diff --git a/admin/dataformats.php b/admin/dataformats.php
index 15c9cf8b0cbb1..26ba215667ca1 100644
--- a/admin/dataformats.php
+++ b/admin/dataformats.php
@@ -42,7 +42,7 @@
 $sortorder = array_flip(array_keys($plugins));
 
 if (!isset($plugins[$name])) {
-    print_error('courseformatnotfound', 'error', $return, $name);
+    throw new \moodle_exception('courseformatnotfound', 'error', $return, $name);
 }
 
 switch ($action) {
diff --git a/admin/environment.php b/admin/environment.php
index 0237e600dfa2b..b1072b3f997a1 100644
--- a/admin/environment.php
+++ b/admin/environment.php
@@ -55,11 +55,11 @@
                     $a = new stdClass();
                     $a->url  = 'https://download.moodle.org/environment/environment.zip';
                     $a->dest = $CFG->dataroot . '/';
-                    print_error($cd->get_error(), 'error', $PAGE->url, $a);
+                    throw new \moodle_exception($cd->get_error(), 'error', $PAGE->url, $a);
                     die();
 
                 } else {
-                    print_error($cd->get_error(), 'error', $PAGE->url);
+                    throw new \moodle_exception($cd->get_error(), 'error', $PAGE->url);
                     die();
                 }
 
diff --git a/admin/index.php b/admin/index.php
index 9732be58ddfe4..27f474bae90ca 100644
--- a/admin/index.php
+++ b/admin/index.php
@@ -174,15 +174,17 @@
 // Check some PHP server settings
 
 if (ini_get_bool('session.auto_start')) {
-    print_error('phpvaroff', 'debug', '', (object)array('name'=>'session.auto_start', 'link'=>$documentationlink));
+    throw new \moodle_exception('phpvaroff', 'debug', '',
+        (object)array('name' => 'session.auto_start', 'link' => $documentationlink));
 }
 
 if (!ini_get_bool('file_uploads')) {
-    print_error('phpvaron', 'debug', '', (object)array('name'=>'file_uploads', 'link'=>$documentationlink));
+    throw new \moodle_exception('phpvaron', 'debug', '',
+        (object)array('name' => 'file_uploads', 'link' => $documentationlink));
 }
 
 if (is_float_problem()) {
-    print_error('phpfloatproblem', 'admin', '', $documentationlink);
+    throw new \moodle_exception('phpfloatproblem', 'admin', '', $documentationlink);
 }
 
 // Set some necessary variables during set-up to avoid PHP warnings later on this page
@@ -203,7 +205,7 @@
 $CFG->target_release = $release;            // used during installation and upgrades
 
 if (!$version or !$release) {
-    print_error('withoutversion', 'debug'); // without version, stop
+    throw new \moodle_exception('withoutversion', 'debug'); // Without version, stop.
 }
 
 if (!core_tables_exist()) {
@@ -275,7 +277,7 @@
     if (!$DB->setup_is_unicodedb()) {
         if (!$DB->change_db_encoding()) {
             // If could not convert successfully, throw error, and prevent installation
-            print_error('unicoderequired', 'admin');
+            throw new \moodle_exception('unicoderequired', 'admin');
         }
     }
 
@@ -297,7 +299,7 @@
 $PAGE->set_context(context_system::instance());
 
 if (empty($CFG->version)) {
-    print_error('missingconfigversion', 'debug');
+    throw new \moodle_exception('missingconfigversion', 'debug');
 }
 
 // Detect config cache inconsistency, this happens when you switch branches on dev servers.
@@ -748,7 +750,7 @@
             redirect("index.php?sessionstarted=1&sessionverify=1&lang=$CFG->lang");
         } else {
             if (empty($SESSION->sessionverify)) {
-                print_error('installsessionerror', 'admin', "index.php?sessionstarted=1&lang=$CFG->lang");
+                throw new \moodle_exception('installsessionerror', 'admin', "index.php?sessionstarted=1&lang=$CFG->lang");
             }
             unset($SESSION->sessionverify);
         }
@@ -765,7 +767,7 @@
     if ($adminuser->password === 'adminsetuppending') {
         // prevent installation hijacking
         if ($adminuser->lastip !== getremoteaddr()) {
-            print_error('installhijacked', 'admin');
+            throw new \moodle_exception('installhijacked', 'admin');
         }
         // login user and let him set password and admin details
         $adminuser->newadminuser = 1;
diff --git a/admin/mnet/access_control.php b/admin/mnet/access_control.php
index edb3b06d32211..c93dc069d7d9a 100644
--- a/admin/mnet/access_control.php
+++ b/admin/mnet/access_control.php
@@ -15,7 +15,7 @@
 admin_externalpage_setup('ssoaccesscontrol');
 
 if (!extension_loaded('openssl')) {
-    print_error('requiresopenssl', 'mnet');
+    throw new \moodle_exception('requiresopenssl', 'mnet');
 }
 
 $sitecontext = context_system::instance();
@@ -35,13 +35,13 @@
 
     // boot if insufficient permission
     if (!has_capability('moodle/user:delete', $sitecontext)) {
-        print_error('nomodifyacl','mnet');
+        throw new \moodle_exception('nomodifyacl', 'mnet');
     }
 
     // fetch the record in question
     $id = required_param('id', PARAM_INT);
     if (!$idrec = $DB->get_record('mnet_sso_access_control', array('id'=>$id))) {
-        print_error('recordnoexists','mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
+        throw new \moodle_exception('recordnoexists', 'mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
     }
 
     switch ($action) {
@@ -56,7 +56,7 @@
             // require the access parameter, and it must be 'allow' or 'deny'
             $accessctrl = trim(strtolower(required_param('accessctrl', PARAM_ALPHA)));
             if ($accessctrl != 'allow' and $accessctrl != 'deny') {
-                print_error('invalidaccessparam', 'mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
+                throw new \moodle_exception('invalidaccessparam', 'mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
             }
 
             if (mnet_update_sso_access_control($idrec->username, $idrec->mnet_host_id, $accessctrl)) {
@@ -71,7 +71,7 @@
             break;
 
         default:
-            print_error('invalidactionparam', 'mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
+            throw new \moodle_exception('invalidactionparam', 'mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
     }
 }
 
@@ -82,7 +82,7 @@
 
     // check permissions and verify form input
     if (!has_capability('moodle/user:delete', $sitecontext)) {
-        print_error('nomodifyacl','mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
+        throw new \moodle_exception('nomodifyacl', 'mnet', "$CFG->wwwroot/$CFG->admin/mnet/access_control.php");
     }
     if (empty($form->username)) {
         $formerror['username'] = get_string('enterausername','mnet');
diff --git a/admin/mnet/index.php b/admin/mnet/index.php
index 5e0240b858244..11a9967c41cc7 100644
--- a/admin/mnet/index.php
+++ b/admin/mnet/index.php
@@ -17,13 +17,13 @@
     if (!extension_loaded('openssl')) {
         echo $OUTPUT->header();
         set_config('mnet_dispatcher_mode', 'off');
-        print_error('requiresopenssl', 'mnet');
+        throw new \moodle_exception('requiresopenssl', 'mnet');
     }
 
     if (!function_exists('curl_init') ) {
         echo $OUTPUT->header();
         set_config('mnet_dispatcher_mode', 'off');
-        print_error('nocurl', 'mnet');
+        throw new \moodle_exception('nocurl', 'mnet');
     }
 
     if (!isset($CFG->mnet_dispatcher_mode)) {
@@ -37,7 +37,7 @@
                 if (set_config('mnet_dispatcher_mode', $form->mode)) {
                     redirect('index.php', get_string('changessaved'));
                 } else {
-                    print_error('invalidaction', '', 'index.php');
+                    throw new \moodle_exception('invalidaction', '', 'index.php');
                 }
             }
         } elseif (!empty($form->submit) && $form->submit == get_string('delete')) {
@@ -63,13 +63,13 @@
 
             if($time < time() - 60) {
                 // fail - you're out of time.
-                print_error ('deleteoutoftime', 'mnet', 'index.php');
+                throw new \moodle_exception ('deleteoutoftime', 'mnet', 'index.php');
                 exit;
             }
 
             if ($key != md5(sha1($mnet->keypair['keypair_PEM']))) {
                 // fail - you're being attacked?
-                print_error ('deletewrongkeyvalue', 'mnet', 'index.php');
+                throw new \moodle_exception ('deletewrongkeyvalue', 'mnet', 'index.php');
                 exit;
             }
 
diff --git a/admin/mnet/peers.php b/admin/mnet/peers.php
index 348a6243f867f..b9313e5701d36 100644
--- a/admin/mnet/peers.php
+++ b/admin/mnet/peers.php
@@ -54,15 +54,15 @@
 $deprecatenotify = mnet_get_deprecation_notice();
 
 if (!extension_loaded('openssl')) {
-    print_error('requiresopenssl', 'mnet');
+    throw new \moodle_exception('requiresopenssl', 'mnet');
 }
 
 if (!function_exists('curl_init') ) {
-    print_error('nocurl', 'mnet');
+    throw new \moodle_exception('nocurl', 'mnet');
 }
 
 if (!function_exists('xmlrpc_encode_request')) {
-    print_error('xmlrpc-missing', 'mnet');
+    throw new \moodle_exception('xmlrpc-missing', 'mnet');
 }
 
 if (!isset($CFG->mnet_dispatcher_mode)) {
@@ -176,7 +176,7 @@
     if ($mnet_peer->commit()) {
         redirect(new moodle_url('/admin/mnet/peers.php', array('hostid' => $mnet_peer->id)), get_string('changessaved'));
     } else {
-        print_error('invalidaction', 'error', 'index.php');
+        throw new \moodle_exception('invalidaction', 'error', 'index.php');
     }
 } else if ($reviewform->is_submitted()) { // submitted, but errors
     echo $OUTPUT->header();
diff --git a/admin/mnet/testclient.php b/admin/mnet/testclient.php
index a12ebb6b71fdb..f370866b0b8b9 100644
--- a/admin/mnet/testclient.php
+++ b/admin/mnet/testclient.php
@@ -18,7 +18,7 @@
 include_once($CFG->dirroot.'/mnet/lib.php');
 
 if ($CFG->mnet_dispatcher_mode === 'off') {
-    print_error('mnetdisabled', 'mnet');
+    throw new \moodle_exception('mnetdisabled', 'mnet');
 }
 
 admin_externalpage_setup('mnettestclient');
@@ -27,7 +27,7 @@
 
 echo $OUTPUT->header();
 if (!extension_loaded('openssl')) {
-    print_error('requiresopenssl', 'mnet', '', NULL, true);
+    throw new \moodle_exception('requiresopenssl', 'mnet', '', null, true);
 }
 
 // optional drilling down parameters
diff --git a/admin/mnet/trustedhosts.php b/admin/mnet/trustedhosts.php
index 5ad348c3b5cac..c72ed8c841f3a 100644
--- a/admin/mnet/trustedhosts.php
+++ b/admin/mnet/trustedhosts.php
@@ -10,7 +10,7 @@
 
     if (!extension_loaded('openssl')) {
         echo $OUTPUT->header();
-        print_error('requiresopenssl', 'mnet', '', NULL, true);
+        throw new \moodle_exception('requiresopenssl', 'mnet', '', null, true);
     }
 
     $site = get_site();
diff --git a/admin/modules.php b/admin/modules.php
index 3a17cf5b78027..b5e61fa276322 100644
--- a/admin/modules.php
+++ b/admin/modules.php
@@ -62,7 +62,7 @@
 /// Get and sort the existing modules
 
     if (!$modules = $DB->get_records('modules', array(), 'name ASC')) {
-        print_error('moduledoesnotexist', 'error');
+        throw new \moodle_exception('moduledoesnotexist', 'error');
     }
 
 /// Print the table of all modules
diff --git a/admin/portfolio.php b/admin/portfolio.php
index 1d5eb691c7943..08939c173d578 100644
--- a/admin/portfolio.php
+++ b/admin/portfolio.php
@@ -116,13 +116,13 @@ function portfolio_action_url($portfolio) {
     $instance = portfolio_instance($portfolio);
     if ($sure) {
         if (!confirm_sesskey()) {
-            print_error('confirmsesskeybad', '', $baseurl);
+            throw new \moodle_exception('confirmsesskeybad', '', $baseurl);
         }
         if ($instance->delete()) {
             $deletedstr = get_string('instancedeleted', 'portfolio');
             redirect($baseurl, $deletedstr, 1);
         } else {
-            print_error('instancenotdeleted', 'portfolio', $baseurl);
+            throw new \moodle_exception('instancenotdeleted', 'portfolio', $baseurl);
         }
         exit;
     } else {
diff --git a/admin/qbehaviours.php b/admin/qbehaviours.php
index e8b87b712b3ff..d047669b92201 100644
--- a/admin/qbehaviours.php
+++ b/admin/qbehaviours.php
@@ -84,7 +84,7 @@
 // Disable.
 if (($disable = optional_param('disable', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($behaviours[$disable])) {
-        print_error('unknownbehaviour', 'question', $thispageurl, $disable);
+        throw new \moodle_exception('unknownbehaviour', 'question', $thispageurl, $disable);
     }
 
     if (array_search($disable, $disabledbehaviours) === false) {
@@ -97,11 +97,11 @@
 // Enable.
 if (($enable = optional_param('enable', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($behaviours[$enable])) {
-        print_error('unknownbehaviour', 'question', $thispageurl, $enable);
+        throw new \moodle_exception('unknownbehaviour', 'question', $thispageurl, $enable);
     }
 
     if (!$archetypal[$enable]) {
-        print_error('cannotenablebehaviour', 'question', $thispageurl, $enable);
+        throw new \moodle_exception('cannotenablebehaviour', 'question', $thispageurl, $enable);
     }
 
     if (($key = array_search($enable, $disabledbehaviours)) !== false) {
@@ -114,7 +114,7 @@
 // Move up in order.
 if (($up = optional_param('up', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($behaviours[$up])) {
-        print_error('unknownbehaviour', 'question', $thispageurl, $up);
+        throw new \moodle_exception('unknownbehaviour', 'question', $thispageurl, $up);
     }
 
     // This function works fine for behaviours, as well as qtypes.
@@ -126,7 +126,7 @@
 // Move down in order.
 if (($down = optional_param('down', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($behaviours[$down])) {
-        print_error('unknownbehaviour', 'question', $thispageurl, $down);
+        throw new \moodle_exception('unknownbehaviour', 'question', $thispageurl, $down);
     }
 
     // This function works fine for behaviours, as well as qtypes.
diff --git a/admin/qtypes.php b/admin/qtypes.php
index f469eac0e46e7..7f0714feeb77c 100644
--- a/admin/qtypes.php
+++ b/admin/qtypes.php
@@ -106,7 +106,7 @@
 // Disable.
 if (($disable = optional_param('disable', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($qtypes[$disable])) {
-        print_error('unknownquestiontype', 'question', $thispageurl, $disable);
+        throw new \moodle_exception('unknownquestiontype', 'question', $thispageurl, $disable);
     }
 
     $class = \core_plugin_manager::resolve_plugininfo_class('qtype');
@@ -117,11 +117,11 @@
 // Enable.
 if (($enable = optional_param('enable', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($qtypes[$enable])) {
-        print_error('unknownquestiontype', 'question', $thispageurl, $enable);
+        throw new \moodle_exception('unknownquestiontype', 'question', $thispageurl, $enable);
     }
 
     if (!$qtypes[$enable]->menu_name()) {
-        print_error('cannotenable', 'question', $thispageurl, $enable);
+        throw new \moodle_exception('cannotenable', 'question', $thispageurl, $enable);
     }
 
     $class = \core_plugin_manager::resolve_plugininfo_class('qtype');
@@ -132,7 +132,7 @@
 // Move up in order.
 if (($up = optional_param('up', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($qtypes[$up])) {
-        print_error('unknownquestiontype', 'question', $thispageurl, $up);
+        throw new \moodle_exception('unknownquestiontype', 'question', $thispageurl, $up);
     }
 
     $neworder = question_reorder_qtypes($sortedqtypes, $up, -1);
@@ -143,7 +143,7 @@
 // Move down in order.
 if (($down = optional_param('down', '', PARAM_PLUGIN)) && confirm_sesskey()) {
     if (!isset($qtypes[$down])) {
-        print_error('unknownquestiontype', 'question', $thispageurl, $down);
+        throw new \moodle_exception('unknownquestiontype', 'question', $thispageurl, $down);
     }
 
     $neworder = question_reorder_qtypes($sortedqtypes, $down, +1);
diff --git a/admin/repository.php b/admin/repository.php
index cf8143480e680..735cbdbca267b 100644
--- a/admin/repository.php
+++ b/admin/repository.php
@@ -152,7 +152,7 @@ function repository_action_url($repository) {
             core_plugin_manager::reset_caches();
             redirect($baseurl);
         } else {
-            print_error('instancenotsaved', 'repository', $baseurl);
+            throw new \moodle_exception('instancenotsaved', 'repository', $baseurl);
         }
         exit;
     } else {
@@ -183,14 +183,14 @@ function repository_action_url($repository) {
     }
 } else if ($action == 'show') {
     if (!confirm_sesskey()) {
-        print_error('confirmsesskeybad', '', $baseurl);
+        throw new \moodle_exception('confirmsesskeybad', '', $baseurl);
     }
     $class = \core_plugin_manager::resolve_plugininfo_class('repository');
     $class::enable_plugin($repository, 1);
     $return = true;
 } else if ($action == 'hide') {
     if (!confirm_sesskey()) {
-        print_error('confirmsesskeybad', '', $baseurl);
+        throw new \moodle_exception('confirmsesskeybad', '', $baseurl);
     }
     $class = \core_plugin_manager::resolve_plugininfo_class('repository');
     $class::enable_plugin($repository, 0);
@@ -200,7 +200,7 @@ function repository_action_url($repository) {
     if ($sure) {
         $PAGE->set_pagetype('admin-repository-' . $repository);
         if (!confirm_sesskey()) {
-            print_error('confirmsesskeybad', '', $baseurl);
+            throw new \moodle_exception('confirmsesskeybad', '', $baseurl);
         }
 
         if ($repositorytype->delete($downloadcontents)) {
@@ -209,7 +209,7 @@ function repository_action_url($repository) {
             core_plugin_manager::reset_caches();
             redirect($baseurl);
         } else {
-            print_error('instancenotdeleted', 'repository', $baseurl);
+            throw new \moodle_exception('instancenotdeleted', 'repository', $baseurl);
         }
         exit;
     } else {
diff --git a/admin/repositoryinstance.php b/admin/repositoryinstance.php
index 70202247f984c..e7b9c77ed1e2a 100644
--- a/admin/repositoryinstance.php
+++ b/admin/repositoryinstance.php
@@ -104,7 +104,7 @@
             core_plugin_manager::reset_caches();
             redirect($parenturl);
         } else {
-            print_error('instancenotsaved', 'repository', $parenturl);
+            throw new \moodle_exception('instancenotsaved', 'repository', $parenturl);
         }
         exit;
     } else {
@@ -134,7 +134,7 @@
             core_plugin_manager::reset_caches();
             redirect($parenturl, $deletedstr, 3);
         } else {
-            print_error('instancenotdeleted', 'repository', $parenturl);
+            throw new \moodle_exception('instancenotdeleted', 'repository', $parenturl);
         }
         exit;
     }
diff --git a/admin/roles/allow.php b/admin/roles/allow.php
index 824cfa81cca39..3447df48c78a0 100644
--- a/admin/roles/allow.php
+++ b/admin/roles/allow.php
@@ -33,7 +33,7 @@
     'view' => 'core_role_allow_view_page'
 );
 if (!isset($classformode[$mode])) {
-    print_error('invalidmode', '', '', $mode);
+    throw new \moodle_exception('invalidmode', '', '', $mode);
 }
 
 $baseurl = new moodle_url('/admin/roles/allow.php', array('mode'=>$mode));
diff --git a/admin/roles/assign.php b/admin/roles/assign.php
index 4dcc69b079b2c..42b5e8e5d7cf4 100644
--- a/admin/roles/assign.php
+++ b/admin/roles/assign.php
@@ -75,7 +75,7 @@
     $a = new stdClass;
     $a->roleid = $roleid;
     $a->context = $contextname;
-    print_error('cannotassignrolehere', '', $context->get_url(), $a);
+    throw new \moodle_exception('cannotassignrolehere', '', $context->get_url(), $a);
 }
 
 // Work out an appropriate page title.
diff --git a/admin/roles/check.php b/admin/roles/check.php
index 23680f7f14185..847898cb5f725 100644
--- a/admin/roles/check.php
+++ b/admin/roles/check.php
@@ -48,7 +48,7 @@
 // Security first.
 require_login($course, false, $cm);
 if (!has_any_capability(array('moodle/role:assign', 'moodle/role:safeoverride', 'moodle/role:override', 'moodle/role:manage'), $context)) {
-    print_error('nopermissions', 'error', '', get_string('checkpermissions', 'core_role'));
+    throw new \moodle_exception('nopermissions', 'error', '', get_string('checkpermissions', 'core_role'));
 }
 
 navigation_node::override_active_url($url);
diff --git a/admin/roles/manage.php b/admin/roles/manage.php
index ad35a1cf9368e..d8d8ba77175cb 100644
--- a/admin/roles/manage.php
+++ b/admin/roles/manage.php
@@ -68,7 +68,7 @@
 switch ($action) {
     case 'delete':
         if (isset($undeletableroles[$roleid])) {
-            print_error('cannotdeletethisrole', '', $baseurl);
+            throw new \moodle_exception('cannotdeletethisrole', '', $baseurl);
         }
         if (!$confirmed) {
             // Show confirmation.
@@ -89,7 +89,7 @@
         }
         if (!delete_role($roleid)) {
             // The delete failed.
-            print_error('cannotdeleterolewithid', 'error', $baseurl, $roleid);
+            throw new \moodle_exception('cannotdeleterolewithid', 'error', $baseurl, $roleid);
         }
         // Deleted a role sitewide...
         redirect($baseurl);
@@ -108,10 +108,10 @@
                 }
             }
             if (is_null($thisrole) || is_null($prevrole)) {
-                print_error('cannotmoverolewithid', 'error', '', $roleid);
+                throw new \moodle_exception('cannotmoverolewithid', 'error', '', $roleid);
             }
             if (!switch_roles($thisrole, $prevrole)) {
-                print_error('cannotmoverolewithid', 'error', '', $roleid);
+                throw new \moodle_exception('cannotmoverolewithid', 'error', '', $roleid);
             }
         }
 
@@ -131,10 +131,10 @@
                 }
             }
             if (is_null($nextrole)) {
-                print_error('cannotmoverolewithid', 'error', '', $roleid);
+                throw new \moodle_exception('cannotmoverolewithid', 'error', '', $roleid);
             }
             if (!switch_roles($thisrole, $nextrole)) {
-                print_error('cannotmoverolewithid', 'error', '', $roleid);
+                throw new \moodle_exception('cannotmoverolewithid', 'error', '', $roleid);
             }
         }
 
diff --git a/admin/roles/override.php b/admin/roles/override.php
index e676a4a08aef8..68a02c4a66ddd 100644
--- a/admin/roles/override.php
+++ b/admin/roles/override.php
@@ -93,7 +93,7 @@
 $PAGE->navbar->add($straction);
 switch ($context->contextlevel) {
     case CONTEXT_SYSTEM:
-        print_error('cannotoverridebaserole', 'error');
+        throw new \moodle_exception('cannotoverridebaserole', 'error');
         break;
     case CONTEXT_USER:
         $fullname = fullname($user, has_capability('moodle/site:viewfullnames', $context));
@@ -124,7 +124,7 @@
     $a = new stdClass;
     $a->roleid = $roleid;
     $a->context = $contextname;
-    print_error('cannotoverriderolehere', '', $context->get_url(), $a);
+    throw new \moodle_exception('cannotoverriderolehere', '', $context->get_url(), $a);
 }
 
 // If we are actually overriding a role, create the table object, and save changes if appropriate.
diff --git a/admin/roles/permissions.php b/admin/roles/permissions.php
index 0a2bd3cd57135..2944d2b438a57 100644
--- a/admin/roles/permissions.php
+++ b/admin/roles/permissions.php
@@ -100,7 +100,7 @@
 $PAGE->activityheader->disable();
 switch ($context->contextlevel) {
     case CONTEXT_SYSTEM:
-        print_error('cannotoverridebaserole', 'error');
+        throw new \moodle_exception('cannotoverridebaserole', 'error');
         break;
     case CONTEXT_USER:
         $fullname = fullname($user, has_capability('moodle/site:viewfullnames', $context));
diff --git a/admin/roles/usersroles.php b/admin/roles/usersroles.php
index 362c4297a12f1..9370bfb64d073 100644
--- a/admin/roles/usersroles.php
+++ b/admin/roles/usersroles.php
@@ -55,7 +55,7 @@
 $canview = has_any_capability(array('moodle/role:assign', 'moodle/role:safeoverride',
         'moodle/role:override', 'moodle/role:manage'), $usercontext);
 if (!$canview) {
-    print_error('nopermissions', 'error', '', get_string('checkpermissions', 'core_role'));
+    throw new \moodle_exception('nopermissions', 'error', '', get_string('checkpermissions', 'core_role'));
 }
 
 if ($userid != $USER->id) {
diff --git a/admin/settings.php b/admin/settings.php
index 19e3acde1b8a6..30c61121b2347 100644
--- a/admin/settings.php
+++ b/admin/settings.php
@@ -23,13 +23,13 @@
     if (moodle_needs_upgrading()) {
         redirect(new moodle_url('/admin/index.php'));
     } else {
-        print_error('sectionerror', 'admin', "$CFG->wwwroot/$CFG->admin/");
+        throw new \moodle_exception('sectionerror', 'admin', "$CFG->wwwroot/$CFG->admin/");
     }
     die;
 }
 
 if (!($settingspage->check_access())) {
-    print_error('accessdenied', 'admin');
+    throw new \moodle_exception('accessdenied', 'admin');
     die;
 }
 
diff --git a/admin/tool/availabilityconditions/index.php b/admin/tool/availabilityconditions/index.php
index ff18a7211baf4..7ddb049f93a0c 100644
--- a/admin/tool/availabilityconditions/index.php
+++ b/admin/tool/availabilityconditions/index.php
@@ -47,7 +47,7 @@
 if (($plugin = optional_param('plugin', '', PARAM_PLUGIN))) {
     require_sesskey();
     if (!array_key_exists($plugin, $plugins)) {
-        print_error('invalidcomponent', 'error', $pageurl);
+        throw new \moodle_exception('invalidcomponent', 'error', $pageurl);
     }
     $action = required_param('action', PARAM_ALPHA);
     switch ($action) {
diff --git a/admin/tool/customlang/classes/form/export.php b/admin/tool/customlang/classes/form/export.php
index 843b09a8fdab8..66ac887951660 100644
--- a/admin/tool/customlang/classes/form/export.php
+++ b/admin/tool/customlang/classes/form/export.php
@@ -44,7 +44,7 @@ public function definition() {
 
         // The export button only appears if a local lang is present.
         if (!check_dir_exists($langdir) || !count(glob("$langdir/*"))) {
-            print_error('nolocallang', 'tool_customlang');
+            throw new \moodle_exception('nolocallang', 'tool_customlang');
         }
 
         $langfiles = scandir($langdir);
diff --git a/admin/tool/customlang/edit.php b/admin/tool/customlang/edit.php
index bfdfd9461a2e0..bcaad8d9f0289 100644
--- a/admin/tool/customlang/edit.php
+++ b/admin/tool/customlang/edit.php
@@ -46,7 +46,7 @@
 
 if (empty($lng)) {
     // PARAM_LANG validation failed
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 // pre-output processing
diff --git a/admin/tool/customlang/index.php b/admin/tool/customlang/index.php
index 09fc31aebd316..f8530dcb94ee4 100644
--- a/admin/tool/customlang/index.php
+++ b/admin/tool/customlang/index.php
@@ -47,7 +47,7 @@
     require_sesskey();
     require_capability('tool/customlang:edit', context_system::instance());
     if (empty($lng)) {
-        print_error('missingparameter');
+        throw new \moodle_exception('missingparameter');
     }
 
     $PAGE->set_cacheable(false);    // progress bar is used here
@@ -70,7 +70,7 @@
     require_sesskey();
     require_capability('tool/customlang:edit', context_system::instance());
     if (empty($lng)) {
-        print_error('missingparameter');
+        throw new \moodle_exception('missingparameter');
     }
 
     if (!$confirm) {
diff --git a/admin/tool/dataprivacy/classes/page_helper.php b/admin/tool/dataprivacy/classes/page_helper.php
index e35686a799ea7..924fd00502388 100644
--- a/admin/tool/dataprivacy/classes/page_helper.php
+++ b/admin/tool/dataprivacy/classes/page_helper.php
@@ -53,7 +53,7 @@ public static function setup(moodle_url $url, $title, $attachtoparentnode = '',
 
         require_login();
         if (isguestuser()) {
-            print_error('noguest');
+            throw new \moodle_exception('noguest');
         }
 
         // TODO Check that data privacy is enabled.
diff --git a/admin/tool/dataprivacy/createdatarequest.php b/admin/tool/dataprivacy/createdatarequest.php
index c95898715963f..a6fe9d2b1be5b 100644
--- a/admin/tool/dataprivacy/createdatarequest.php
+++ b/admin/tool/dataprivacy/createdatarequest.php
@@ -35,7 +35,7 @@
 
 require_login();
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 // Return URL and context.
diff --git a/admin/tool/dataprivacy/mydatarequests.php b/admin/tool/dataprivacy/mydatarequests.php
index 037e244708e64..a498c0d66497c 100644
--- a/admin/tool/dataprivacy/mydatarequests.php
+++ b/admin/tool/dataprivacy/mydatarequests.php
@@ -36,7 +36,7 @@
 
 require_login();
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 $usercontext = context_user::instance($USER->id);
diff --git a/admin/tool/generator/classes/testplan_backend.php b/admin/tool/generator/classes/testplan_backend.php
index d4bde532a4a01..3d74e3e3d0861 100644
--- a/admin/tool/generator/classes/testplan_backend.php
+++ b/admin/tool/generator/classes/testplan_backend.php
@@ -186,7 +186,7 @@ protected static function generate_users_file($targetcourseid, $updateuserspassw
         $planusers = self::$users[$size] ?? 0;
         $users = get_enrolled_users($coursecontext, '', 0, 'u.id, u.username, u.auth', 'u.username ASC', 0, $planusers);
         if (!$users) {
-            print_error('coursewithoutusers', 'tool_generator');
+            throw new \moodle_exception('coursewithoutusers', 'tool_generator');
         }
 
         $lines = array();
@@ -196,7 +196,7 @@ protected static function generate_users_file($targetcourseid, $updateuserspassw
             if ($updateuserspassword) {
                 $userauth = get_auth_plugin($user->auth);
                 if (!$userauth->user_update_password($user, $CFG->tool_generator_users_password)) {
-                    print_error('errorpasswordupdate', 'auth');
+                    throw new \moodle_exception('errorpasswordupdate', 'auth');
                 }
             }
 
@@ -249,19 +249,19 @@ protected static function get_course_test_data($targetcourseid) {
 
         // Getting the first page module instance.
         if (!$pages = $courseinfo->get_instances_of('page')) {
-            print_error('error_nopageinstances', 'tool_generator');
+            throw new \moodle_exception('error_nopageinstances', 'tool_generator');
         }
         $data->pageid = reset($pages)->id;
 
         // Getting the first forum module instance and it's first discussion and reply as well.
         if (!$forums = $courseinfo->get_instances_of('forum')) {
-            print_error('error_noforuminstances', 'tool_generator');
+            throw new \moodle_exception('error_noforuminstances', 'tool_generator');
         }
         $forum = reset($forums);
 
         // Getting the first discussion (and reply).
         if (!$discussions = forum_get_discussions($forum, 'd.timemodified ASC', false, -1, 1)) {
-            print_error('error_noforumdiscussions', 'tool_generator');
+            throw new \moodle_exception('error_noforumdiscussions', 'tool_generator');
         }
         $discussion = reset($discussions);
 
diff --git a/admin/tool/licensemanager/classes/manager.php b/admin/tool/licensemanager/classes/manager.php
index 2f3ad2cee203d..85d37544cf5c8 100644
--- a/admin/tool/licensemanager/classes/manager.php
+++ b/admin/tool/licensemanager/classes/manager.php
@@ -152,14 +152,14 @@ private function edit(string $action, string $licenseshortname) : bool {
             if ($action == self::ACTION_CREATE) {
                 // Check that license shortname isn't already in use.
                 if (!empty(license_manager::get_license_by_shortname($data->shortname))) {
-                    print_error('duplicatelicenseshortname', 'tool_licensemanager',
+                    throw new \moodle_exception('duplicatelicenseshortname', 'tool_licensemanager',
                         helper::get_licensemanager_url(),
                         $data->shortname);
                 }
                 $license->shortname = $data->shortname;
             } else {
                 if (empty(license_manager::get_license_by_shortname($licenseshortname))) {
-                    print_error('licensenotfoundshortname', 'license',
+                    throw new \moodle_exception('licensenotfoundshortname', 'license',
                         helper::get_licensemanager_url(),
                         $licenseshortname);
                 }
diff --git a/admin/tool/mobile/logout.php b/admin/tool/mobile/logout.php
index 17a768ac7775a..ebadfec87ed65 100644
--- a/admin/tool/mobile/logout.php
+++ b/admin/tool/mobile/logout.php
@@ -27,7 +27,7 @@
 require_once($CFG->dirroot . '/webservice/lib.php');
 
 if (!$CFG->enablemobilewebservice) {
-    print_error('enablewsdescription', 'webservice');
+    throw new \moodle_exception('enablewsdescription', 'webservice');
 }
 
 require_login(null, false);
diff --git a/admin/tool/mobile/subscription.php b/admin/tool/mobile/subscription.php
index 6dca2c5e00fa7..8eca0d4843125 100644
--- a/admin/tool/mobile/subscription.php
+++ b/admin/tool/mobile/subscription.php
@@ -30,11 +30,11 @@
 
 // Check Mobile web services enabled. This page should not be linked in that case, but avoid just in case.
 if (!$CFG->enablemobilewebservice) {
-    print_error('enablewsdescription', 'webservice');
+    throw new \moodle_exception('enablewsdescription', 'webservice');
 }
 // Check is this feature is globaly disabled.
 if (!empty($CFG->disablemobileappsubscription)) {
-    print_error('disabled', 'admin');
+    throw new \moodle_exception('disabled', 'admin');
 }
 
 $subscriptiondata = \tool_mobile\api::get_subscription_information();
diff --git a/admin/tool/monitor/index.php b/admin/tool/monitor/index.php
index 5392fd628054c..2adbd29a3bb7d 100644
--- a/admin/tool/monitor/index.php
+++ b/admin/tool/monitor/index.php
@@ -46,7 +46,7 @@
             $choose = true;
         } else {
             // return error.
-            print_error('rulenopermission', 'tool_monitor');
+            throw new \moodle_exception('rulenopermission', 'tool_monitor');
         }
     }
 } else {
diff --git a/admin/tool/moodlenet/import.php b/admin/tool/moodlenet/import.php
index 1b57ce9d6de93..c4a9df2af1f8c 100644
--- a/admin/tool/moodlenet/import.php
+++ b/admin/tool/moodlenet/import.php
@@ -38,7 +38,7 @@
 
 // The integration must be enabled for this import endpoint to be active.
 if (!get_config('tool_moodlenet', 'enablemoodlenet')) {
-    print_error('moodlenetnotenabled', 'tool_moodlenet');
+    throw new \moodle_exception('moodlenetnotenabled', 'tool_moodlenet');
 }
 
 $resourceurl = required_param('resourceurl', PARAM_URL);
@@ -82,4 +82,4 @@
 }
 
 // Invalid or missing POST data. Show an error to the user.
-print_error('missinginvalidpostdata', 'tool_moodlenet');
+throw new \moodle_exception('missinginvalidpostdata', 'tool_moodlenet');
diff --git a/admin/tool/moodlenet/index.php b/admin/tool/moodlenet/index.php
index 5680d19a8dc91..5103730e0528a 100644
--- a/admin/tool/moodlenet/index.php
+++ b/admin/tool/moodlenet/index.php
@@ -44,7 +44,7 @@
     require_capability('moodle/course:manageactivities', context_course::instance($importinfo->get_config()->course));
 }
 if (!get_config('tool_moodlenet', 'enablemoodlenet')) {
-    print_error('moodlenetnotenabled', 'tool_moodlenet');
+    throw new \moodle_exception('moodlenetnotenabled', 'tool_moodlenet');
 }
 
 // Handle the form submits.
@@ -73,7 +73,7 @@
             $context = import_backup_helper::get_context_for_user($USER->id);
 
             if (is_null($context)) {
-                print_error('nopermissions', 'error', '', get_string('restore:uploadfile', 'core_role'));
+                throw new \moodle_exception('nopermissions', 'error', '', get_string('restore:uploadfile', 'core_role'));
             }
         } else {
             $context = context_course::instance($importinfo->get_config()->course);
diff --git a/admin/tool/moodlenet/options.php b/admin/tool/moodlenet/options.php
index a510f53e20697..2245150439bbc 100644
--- a/admin/tool/moodlenet/options.php
+++ b/admin/tool/moodlenet/options.php
@@ -59,7 +59,7 @@
 require_login($config->course, false);
 require_capability('moodle/course:manageactivities', context_course::instance($config->course));
 if (!get_config('tool_moodlenet', 'enablemoodlenet')) {
-    print_error('moodlenetnotenabled', 'tool_moodlenet');
+    throw new \moodle_exception('moodlenetnotenabled', 'tool_moodlenet');
 }
 
 // If the user cancelled, break early.
diff --git a/admin/tool/moodlenet/select.php b/admin/tool/moodlenet/select.php
index 704de2ff19c63..1a01ec0e245b0 100644
--- a/admin/tool/moodlenet/select.php
+++ b/admin/tool/moodlenet/select.php
@@ -31,7 +31,7 @@
 // Access control.
 require_login();
 if (!get_config('tool_moodlenet', 'enablemoodlenet')) {
-    print_error('moodlenetnotenabled', 'tool_moodlenet');
+    throw new \moodle_exception('moodlenetnotenabled', 'tool_moodlenet');
 }
 
 if (is_null($importinfo = import_info::load($id))) {
diff --git a/admin/tool/multilangupgrade/index.php b/admin/tool/multilangupgrade/index.php
index 0cc6b4144f31a..2ca508e579b43 100644
--- a/admin/tool/multilangupgrade/index.php
+++ b/admin/tool/multilangupgrade/index.php
@@ -52,7 +52,7 @@
 
 
 if (!$tables = $DB->get_tables() ) {    // No tables yet at all.
-    print_error('notables', 'debug');
+    throw new \moodle_exception('notables', 'debug');
 }
 
 echo $OUTPUT->box_start();
diff --git a/admin/tool/oauth2/endpoints.php b/admin/tool/oauth2/endpoints.php
index bb39a821253a6..ac728732a8be0 100644
--- a/admin/tool/oauth2/endpoints.php
+++ b/admin/tool/oauth2/endpoints.php
@@ -45,7 +45,7 @@
 
 $issuer = \core\oauth2\api::get_issuer($issuerid);
 if (!$issuer) {
-    print_error('invaliddata');
+    throw new \moodle_exception('invaliddata');
 }
 $PAGE->navbar->override_active_url(new moodle_url('/admin/tool/oauth2/issuers.php'), true);
 
diff --git a/admin/tool/oauth2/issuers.php b/admin/tool/oauth2/issuers.php
index df19faddcaaa3..dff41e066027b 100644
--- a/admin/tool/oauth2/issuers.php
+++ b/admin/tool/oauth2/issuers.php
@@ -45,7 +45,7 @@
 if ($issuerid) {
     $issuer = \core\oauth2\api::get_issuer($issuerid);
     if (!$issuer) {
-        print_error('invaliddata');
+        throw new \moodle_exception('invaliddata');
     }
 }
 
diff --git a/admin/tool/oauth2/userfieldmappings.php b/admin/tool/oauth2/userfieldmappings.php
index 28fc5a6feadfd..0a51c365e7342 100644
--- a/admin/tool/oauth2/userfieldmappings.php
+++ b/admin/tool/oauth2/userfieldmappings.php
@@ -45,7 +45,7 @@
 
 $issuer = \core\oauth2\api::get_issuer($issuerid);
 if (!$issuer) {
-    print_error('invaliddata');
+    throw new \moodle_exception('invaliddata');
 }
 $PAGE->navbar->override_active_url(new moodle_url('/admin/tool/oauth2/issuers.php'), true);
 
diff --git a/admin/tool/policy/accept.php b/admin/tool/policy/accept.php
index 42f07603d5834..ed19077e70aed 100644
--- a/admin/tool/policy/accept.php
+++ b/admin/tool/policy/accept.php
@@ -32,7 +32,7 @@
 
 require_login();
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 $context = context_system::instance();
 
diff --git a/admin/tool/policy/user.php b/admin/tool/policy/user.php
index 104d2591d2887..2e3676a6700db 100644
--- a/admin/tool/policy/user.php
+++ b/admin/tool/policy/user.php
@@ -31,7 +31,7 @@
 require_login();
 $userid = $userid ?: $USER->id;
 if (isguestuser() || isguestuser($userid)) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 $context = context_user::instance($userid);
 if ($userid != $USER->id) {
diff --git a/admin/tool/recyclebin/index.php b/admin/tool/recyclebin/index.php
index 1c587ff741e8e..24334b184de97 100644
--- a/admin/tool/recyclebin/index.php
+++ b/admin/tool/recyclebin/index.php
@@ -70,12 +70,12 @@
     break;
 
     default:
-        print_error('invalidcontext', 'tool_recyclebin');
+        throw new \moodle_exception('invalidcontext', 'tool_recyclebin');
     break;
 }
 
 if (!$recyclebin::is_enabled()) {
-    print_error('notenabled', 'tool_recyclebin');
+    throw new \moodle_exception('notenabled', 'tool_recyclebin');
 }
 
 $PAGE->set_url('/admin/tool/recyclebin/index.php', array(
@@ -101,7 +101,7 @@
                 $recyclebin->restore_item($item);
                 redirect($PAGE->url, get_string('alertrestored', 'tool_recyclebin', $item), 2);
             } else {
-                print_error('nopermissions', 'error');
+                throw new \moodle_exception('nopermissions', 'error');
             }
         break;
 
@@ -111,7 +111,7 @@
                 $recyclebin->delete_item($item);
                 redirect($PAGE->url, get_string('alertdeleted', 'tool_recyclebin', $item), 2);
             } else {
-                print_error('nopermissions', 'error');
+                throw new \moodle_exception('nopermissions', 'error');
             }
         break;
 
diff --git a/admin/tool/task/clear_fail_delay.php b/admin/tool/task/clear_fail_delay.php
index 8f357b8a7ba1d..032be004634fc 100644
--- a/admin/tool/task/clear_fail_delay.php
+++ b/admin/tool/task/clear_fail_delay.php
@@ -36,7 +36,7 @@
 $taskname = required_param('task', PARAM_RAW_TRIMMED);
 $task = \core\task\manager::get_scheduled_task($taskname);
 if (!$task) {
-    print_error('cannotfindinfo', 'error', $taskname);
+    throw new \moodle_exception('cannotfindinfo', 'error', $taskname);
 }
 
 $returnurl = new moodle_url('/admin/tool/task/scheduledtasks.php',
diff --git a/admin/tool/task/scheduledtasks.php b/admin/tool/task/scheduledtasks.php
index cc8b3105f3d8a..67005fdea2927 100644
--- a/admin/tool/task/scheduledtasks.php
+++ b/admin/tool/task/scheduledtasks.php
@@ -38,7 +38,7 @@
 if ($taskname) {
     $task = \core\task\manager::get_scheduled_task($taskname);
     if (!$task) {
-        print_error('invaliddata');
+        throw new \moodle_exception('invaliddata');
     }
 }
 
diff --git a/admin/tool/uploadcourse/cli/uploadcourse.php b/admin/tool/uploadcourse/cli/uploadcourse.php
index 1e9394de24de2..5068670d8b2c9 100644
--- a/admin/tool/uploadcourse/cli/uploadcourse.php
+++ b/admin/tool/uploadcourse/cli/uploadcourse.php
@@ -193,9 +193,9 @@
 $readcount = $cir->load_csv_content($content, $options['encoding'], $options['delimiter']);
 unset($content);
 if ($readcount === false) {
-    print_error('csvfileerror', 'tool_uploadcourse', '', $cir->get_error());
+    throw new \moodle_exception('csvfileerror', 'tool_uploadcourse', '', $cir->get_error());
 } else if ($readcount == 0) {
-    print_error('csvemptyfile', 'error', '', $cir->get_error());
+    throw new \moodle_exception('csvemptyfile', 'error', '', $cir->get_error());
 }
 $processor = new tool_uploadcourse_processor($cir, $processoroptions, $defaults);
 $processor->execute(new tool_uploadcourse_tracker(tool_uploadcourse_tracker::OUTPUT_PLAIN));
diff --git a/admin/tool/uploadcourse/index.php b/admin/tool/uploadcourse/index.php
index 8c2ccfd9caa14..8b26e54196d9b 100644
--- a/admin/tool/uploadcourse/index.php
+++ b/admin/tool/uploadcourse/index.php
@@ -42,9 +42,9 @@
         $readcount = $cir->load_csv_content($content, $form1data->encoding, $form1data->delimiter_name);
         unset($content);
         if ($readcount === false) {
-            print_error('csvfileerror', 'tool_uploadcourse', $returnurl, $cir->get_error());
+            throw new \moodle_exception('csvfileerror', 'tool_uploadcourse', $returnurl, $cir->get_error());
         } else if ($readcount == 0) {
-            print_error('csvemptyfile', 'error', $returnurl, $cir->get_error());
+            throw new \moodle_exception('csvemptyfile', 'error', $returnurl, $cir->get_error());
         }
     } else {
         echo $OUTPUT->header();
diff --git a/admin/tool/uploaduser/index.php b/admin/tool/uploaduser/index.php
index a0ef7ab16f4f6..325e24d626591 100644
--- a/admin/tool/uploaduser/index.php
+++ b/admin/tool/uploaduser/index.php
@@ -54,7 +54,7 @@
         unset($content);
 
         if (!is_null($csvloaderror)) {
-            print_error('csvloaderror', '', $returnurl, $csvloaderror);
+            throw new \moodle_exception('csvloaderror', '', $returnurl, $csvloaderror);
         }
         // Continue to form2.
 
diff --git a/admin/tool/uploaduser/locallib.php b/admin/tool/uploaduser/locallib.php
index 607f64bd0040b..0a62791488e89 100644
--- a/admin/tool/uploaduser/locallib.php
+++ b/admin/tool/uploaduser/locallib.php
@@ -192,12 +192,12 @@ function uu_validate_user_upload_columns(csv_import_reader $cir, $stdfields, $pr
     if (empty($columns)) {
         $cir->close();
         $cir->cleanup();
-        print_error('cannotreadtmpfile', 'error', $returnurl);
+        throw new \moodle_exception('cannotreadtmpfile', 'error', $returnurl);
     }
     if (count($columns) < 2) {
         $cir->close();
         $cir->cleanup();
-        print_error('csvfewcolumns', 'error', $returnurl);
+        throw new \moodle_exception('csvfewcolumns', 'error', $returnurl);
     }
 
     // test columns
@@ -240,12 +240,12 @@ function uu_validate_user_upload_columns(csv_import_reader $cir, $stdfields, $pr
         } else {
             $cir->close();
             $cir->cleanup();
-            print_error('invalidfieldname', 'error', $returnurl, $field);
+            throw new \moodle_exception('invalidfieldname', 'error', $returnurl, $field);
         }
         if (in_array($newfield, $processed)) {
             $cir->close();
             $cir->cleanup();
-            print_error('duplicatefieldname', 'error', $returnurl, $newfield);
+            throw new \moodle_exception('duplicatefieldname', 'error', $returnurl, $newfield);
         }
         $processed[$key] = $newfield;
     }
diff --git a/admin/tool/uploaduser/picture.php b/admin/tool/uploaduser/picture.php
index a1d0d3de82fd3..6c5923b5e44b3 100644
--- a/admin/tool/uploaduser/picture.php
+++ b/admin/tool/uploaduser/picture.php
@@ -41,7 +41,7 @@
 $site = get_site();
 
 if (!$adminuser = get_admin()) {
-    print_error('noadmins', 'error');
+    throw new \moodle_exception('noadmins', 'error');
 }
 
 $strfile = get_string('file');
diff --git a/admin/tool/xmldb/actions/edit_field_save/edit_field_save.class.php b/admin/tool/xmldb/actions/edit_field_save/edit_field_save.class.php
index 6d0cec5a2b0ec..40bbeee44c910 100644
--- a/admin/tool/xmldb/actions/edit_field_save/edit_field_save.class.php
+++ b/admin/tool/xmldb/actions/edit_field_save/edit_field_save.class.php
@@ -76,7 +76,7 @@ function invoke() {
         // Do the job, setting result as needed
 
         if (!data_submitted()) { // Basic prevention
-            print_error('wrongcall', 'error');
+            throw new \moodle_exception('wrongcall', 'error');
         }
 
         // Get parameters
diff --git a/admin/tool/xmldb/actions/edit_index_save/edit_index_save.class.php b/admin/tool/xmldb/actions/edit_index_save/edit_index_save.class.php
index 515cbbbe7b9db..fb2e55a3e3e90 100644
--- a/admin/tool/xmldb/actions/edit_index_save/edit_index_save.class.php
+++ b/admin/tool/xmldb/actions/edit_index_save/edit_index_save.class.php
@@ -73,7 +73,7 @@ function invoke() {
         // Do the job, setting result as needed
 
         if (!data_submitted()) { // Basic prevention
-            print_error('wrongcall', 'error');
+            throw new \moodle_exception('wrongcall', 'error');
         }
 
         // Get parameters
diff --git a/admin/tool/xmldb/actions/edit_key_save/edit_key_save.class.php b/admin/tool/xmldb/actions/edit_key_save/edit_key_save.class.php
index 378754aa1040d..7dd00e72728b3 100644
--- a/admin/tool/xmldb/actions/edit_key_save/edit_key_save.class.php
+++ b/admin/tool/xmldb/actions/edit_key_save/edit_key_save.class.php
@@ -79,7 +79,7 @@ function invoke() {
         // Do the job, setting result as needed
 
         if (!data_submitted()) { // Basic prevention
-            print_error('wrongcall', 'error');
+            throw new \moodle_exception('wrongcall', 'error');
         }
 
         // Get parameters
diff --git a/admin/tool/xmldb/actions/edit_table_save/edit_table_save.class.php b/admin/tool/xmldb/actions/edit_table_save/edit_table_save.class.php
index 929e26fa0f07f..1332570a8c306 100644
--- a/admin/tool/xmldb/actions/edit_table_save/edit_table_save.class.php
+++ b/admin/tool/xmldb/actions/edit_table_save/edit_table_save.class.php
@@ -67,7 +67,7 @@ function invoke() {
         // Do the job, setting result as needed
 
         if (!data_submitted()) { // Basic prevention
-            print_error('wrongcall', 'error');
+            throw new \moodle_exception('wrongcall', 'error');
         }
 
         // Get parameters
diff --git a/admin/tool/xmldb/actions/edit_xml_file_save/edit_xml_file_save.class.php b/admin/tool/xmldb/actions/edit_xml_file_save/edit_xml_file_save.class.php
index 0a52dffab1896..a117fdfa40112 100644
--- a/admin/tool/xmldb/actions/edit_xml_file_save/edit_xml_file_save.class.php
+++ b/admin/tool/xmldb/actions/edit_xml_file_save/edit_xml_file_save.class.php
@@ -63,7 +63,7 @@ function invoke() {
         // Do the job, setting result as needed
 
         if (!data_submitted()) { // Basic prevention
-            print_error('wrongcall', 'error');
+            throw new \moodle_exception('wrongcall', 'error');
         }
 
         // Get parameters
diff --git a/admin/tool/xmldb/index.php b/admin/tool/xmldb/index.php
index 4dd92102e4b6f..a4336cba678b9 100644
--- a/admin/tool/xmldb/index.php
+++ b/admin/tool/xmldb/index.php
@@ -104,16 +104,16 @@
             }
         } else {
             // TODO: need more detailed error info
-            print_error('xmldberror');
+            throw new \moodle_exception('xmldberror');
         }
     } else {
         $a = new stdClass();
         $a->action = $action;
         $a->actionclass = $actionclass;
-        print_error('cannotinstantiateclass', 'tool_xmldb', '', $a);
+        throw new \moodle_exception('cannotinstantiateclass', 'tool_xmldb', '', $a);
     }
 } else {
-    print_error('invalidaction');
+    throw new \moodle_exception('invalidaction');
 }
 
 if ($xmldb_action->getDoesGenerate() != ACTION_GENERATE_XML) {
diff --git a/admin/user.php b/admin/user.php
index cc2a6121b48d1..910feed19d08c 100644
--- a/admin/user.php
+++ b/admin/user.php
@@ -27,7 +27,7 @@
     $site = get_site();
 
     if (!has_capability('moodle/user:update', $sitecontext) and !has_capability('moodle/user:delete', $sitecontext)) {
-        print_error('nopermissions', 'error', '', 'edit/delete users');
+        throw new \moodle_exception('nopermissions', 'error', '', 'edit/delete users');
     }
 
     $stredit   = get_string('edit');
@@ -50,7 +50,7 @@
     if ($confirmuser and confirm_sesskey()) {
         require_capability('moodle/user:update', $sitecontext);
         if (!$user = $DB->get_record('user', array('id'=>$confirmuser, 'mnethostid'=>$CFG->mnet_localhost_id))) {
-            print_error('nousers');
+            throw new \moodle_exception('nousers');
         }
 
         $auth = get_auth_plugin($user->auth);
@@ -66,12 +66,12 @@
 
     } else if ($resendemail && confirm_sesskey()) {
         if (!$user = $DB->get_record('user', ['id' => $resendemail, 'mnethostid' => $CFG->mnet_localhost_id, 'deleted' => 0])) {
-            print_error('nousers');
+            throw new \moodle_exception('nousers');
         }
 
         // Prevent spamming users who are already confirmed.
         if ($user->confirmed) {
-            print_error('alreadyconfirmed');
+            throw new \moodle_exception('alreadyconfirmed', 'moodle');
         }
 
         $returnmsg = get_string('emailconfirmsentsuccess');
@@ -88,10 +88,10 @@
         $user = $DB->get_record('user', array('id'=>$delete, 'mnethostid'=>$CFG->mnet_localhost_id), '*', MUST_EXIST);
 
         if ($user->deleted) {
-            print_error('usernotdeleteddeleted', 'error');
+            throw new \moodle_exception('usernotdeleteddeleted', 'error');
         }
         if (is_siteadmin($user->id)) {
-            print_error('useradminodelete', 'error');
+            throw new \moodle_exception('useradminodelete', 'error');
         }
 
         if ($confirm != md5($delete)) {
@@ -118,17 +118,17 @@
         }
     } else if ($acl and confirm_sesskey()) {
         if (!has_capability('moodle/user:update', $sitecontext)) {
-            print_error('nopermissions', 'error', '', 'modify the NMET access control list');
+            throw new \moodle_exception('nopermissions', 'error', '', 'modify the NMET access control list');
         }
         if (!$user = $DB->get_record('user', array('id'=>$acl))) {
-            print_error('nousers', 'error');
+            throw new \moodle_exception('nousers', 'error');
         }
         if (!is_mnet_remote_user($user)) {
-            print_error('usermustbemnet', 'error');
+            throw new \moodle_exception('usermustbemnet', 'error');
         }
         $accessctrl = strtolower(required_param('accessctrl', PARAM_ALPHA));
         if ($accessctrl != 'allow' and $accessctrl != 'deny') {
-            print_error('invalidaccessparameter', 'error');
+            throw new \moodle_exception('invalidaccessparameter', 'error');
         }
         $aclrecord = $DB->get_record('mnet_sso_access_control', array('username'=>$user->username, 'mnet_host_id'=>$user->mnethostid));
         if (empty($aclrecord)) {
diff --git a/admin/user/user_bulk_message.php b/admin/user/user_bulk_message.php
index 3ef1e5f7242ba..c18c010088af7 100644
--- a/admin/user/user_bulk_message.php
+++ b/admin/user/user_bulk_message.php
@@ -17,7 +17,7 @@
 }
 
 if (empty($CFG->messaging)) {
-    print_error('messagingdisable', 'error');
+    throw new \moodle_exception('messagingdisable', 'error');
 }
 
 $PAGE->set_primary_active_tab('siteadminnode');
diff --git a/analytics/classes/model_config.php b/analytics/classes/model_config.php
index 67218507d9d76..a715a8262ff18 100644
--- a/analytics/classes/model_config.php
+++ b/analytics/classes/model_config.php
@@ -80,7 +80,7 @@ public function export(string $zipfilename, bool $includeweights = true) : strin
         $exporttmpdir = make_request_directory();
         $jsonfilepath = $exporttmpdir . DIRECTORY_SEPARATOR . 'model-config.json';
         if (!file_put_contents($jsonfilepath, json_encode($modeldata))) {
-            print_error('errornoexportconfig', 'analytics');
+            throw new \moodle_exception('errornoexportconfig', 'analytics');
         }
         $zipfiles[self::CONFIG_FILE_NAME] = $jsonfilepath;
 
diff --git a/auth/db/auth.php b/auth/db/auth.php
index 96aad433f12b2..bb9ed70363d8f 100644
--- a/auth/db/auth.php
+++ b/auth/db/auth.php
@@ -502,7 +502,7 @@ function user_exists($username) {
                                  WHERE {$this->config->fielduser} = '".$this->ext_addslashes($extusername)."' ");
 
         if (!$rs) {
-            print_error('auth_dbcantconnect','auth_db');
+            throw new \moodle_exception('auth_dbcantconnect', 'auth_db');
         } else if (!$rs->EOF) {
             // User exists externally.
             $result = true;
@@ -525,7 +525,7 @@ function get_userlist() {
                                   FROM {$this->config->table} ");
 
         if (!$rs) {
-            print_error('auth_dbcantconnect','auth_db');
+            throw new \moodle_exception('auth_dbcantconnect', 'auth_db');
         } else if (!$rs->EOF) {
             while ($rec = $rs->FetchRow()) {
                 $rec = array_change_key_case((array)$rec, CASE_LOWER);
@@ -607,7 +607,7 @@ function user_update($olduser, $newuser) {
                        SET ".implode(',', $update)."
                      WHERE {$this->config->fielduser} = ?";
             if (!$authdb->Execute($sql, array($this->ext_addslashes($extusername)))) {
-                print_error('auth_dbupdateerror', 'auth_db');
+                throw new \moodle_exception('auth_dbupdateerror', 'auth_db');
             }
         }
         $authdb->Close();
diff --git a/auth/email/auth.php b/auth/email/auth.php
index 1998ba0572f3c..42a6e2d99608b 100644
--- a/auth/email/auth.php
+++ b/auth/email/auth.php
@@ -139,7 +139,7 @@ public function user_signup_with_confirmation($user, $notify=true, $confirmation
         \core\event\user_created::create_from_userid($user->id)->trigger();
 
         if (! send_confirmation_email($user, $confirmationurl)) {
-            print_error('auth_emailnoemail', 'auth_email');
+            throw new \moodle_exception('auth_emailnoemail', 'auth_email');
         }
 
         if ($notify) {
diff --git a/auth/ldap/auth.php b/auth/ldap/auth.php
index 9eb3a860421fc..3dfd0564d5a56 100644
--- a/auth/ldap/auth.php
+++ b/auth/ldap/auth.php
@@ -148,7 +148,7 @@ public function auth_plugin_ldap() {
      */
     function user_login($username, $password) {
         if (! function_exists('ldap_bind')) {
-            print_error('auth_ldapnotinstalled', 'auth_ldap');
+            throw new \moodle_exception('auth_ldapnotinstalled', 'auth_ldap');
             return false;
         }
 
@@ -450,12 +450,12 @@ function user_create($userobject, $plainpass) {
                 // strings (UCS-2 Little Endian format) and surrounded with
                 // double quotes. See http://support.microsoft.com/?kbid=269190
                 if (!function_exists('mb_convert_encoding')) {
-                    print_error('auth_ldap_no_mbstring', 'auth_ldap');
+                    throw new \moodle_exception('auth_ldap_no_mbstring', 'auth_ldap');
                 }
 
                 // Check for invalid sAMAccountName characters.
                 if (preg_match('#[/\\[\]:;|=,+*?<>@"]#', $extusername)) {
-                    print_error ('auth_ldap_ad_invalidchars', 'auth_ldap');
+                    throw new \moodle_exception ('auth_ldap_ad_invalidchars', 'auth_ldap');
                 }
 
                 // First create the user account, and mark it as disabled.
@@ -465,7 +465,7 @@ function user_create($userobject, $plainpass) {
                                                  AUTH_AD_ACCOUNTDISABLE;
                 $userdn = 'cn='.ldap_addslashes($extusername).','.$this->config->create_context;
                 if (!ldap_add($ldapconnection, $userdn, $newuser)) {
-                    print_error('auth_ldap_ad_create_req', 'auth_ldap');
+                    throw new \moodle_exception('auth_ldap_ad_create_req', 'auth_ldap');
                 }
 
                 // Now set the password
@@ -475,12 +475,12 @@ function user_create($userobject, $plainpass) {
                 if(!ldap_modify($ldapconnection, $userdn, $newuser)) {
                     // Something went wrong: delete the user account and error out
                     ldap_delete ($ldapconnection, $userdn);
-                    print_error('auth_ldap_ad_create_req', 'auth_ldap');
+                    throw new \moodle_exception('auth_ldap_ad_create_req', 'auth_ldap');
                 }
                 $uadd = true;
                 break;
             default:
-               print_error('auth_ldap_unsupportedusertype', 'auth_ldap', '', $this->config->user_type_name);
+               throw new \moodle_exception('auth_ldap_unsupportedusertype', 'auth_ldap', '', $this->config->user_type_name);
         }
         $this->ldap_close();
         return $uadd;
@@ -528,14 +528,14 @@ function user_signup($user, $notify=true) {
         require_once($CFG->dirroot.'/user/lib.php');
 
         if ($this->user_exists($user->username)) {
-            print_error('auth_ldap_user_exists', 'auth_ldap');
+            throw new \moodle_exception('auth_ldap_user_exists', 'auth_ldap');
         }
 
         $plainslashedpassword = $user->password;
         unset($user->password);
 
         if (! $this->user_create($user, $plainslashedpassword)) {
-            print_error('auth_ldap_create_error', 'auth_ldap');
+            throw new \moodle_exception('auth_ldap_create_error', 'auth_ldap');
         }
 
         $user->id = user_create_user($user, false, false);
@@ -558,7 +558,7 @@ function user_signup($user, $notify=true) {
         \core\event\user_created::create_from_userid($user->id)->trigger();
 
         if (! send_confirmation_email($user)) {
-            print_error('noemail', 'auth_ldap');
+            throw new \moodle_exception('noemail', 'auth_ldap');
         }
 
         if ($notify) {
@@ -1018,7 +1018,7 @@ function user_activate($username) {
                                                  & (~AUTH_AD_ACCOUNTDISABLE);
                 break;
             default:
-                print_error('user_activatenotsupportusertype', 'auth_ldap', '', $this->config->user_type_name);
+                throw new \moodle_exception('user_activatenotsupportusertype', 'auth_ldap', '', $this->config->user_type_name);
         }
         $result = ldap_modify($ldapconnection, $userdn, $newinfo);
         $this->ldap_close();
@@ -1453,7 +1453,7 @@ function ldap_expirationtime2unix ($time, $ldapconnection, $user_dn) {
                 $result = $this->ldap_get_ad_pwdexpire($time, $ldapconnection, $user_dn);
                 break;
             default:
-                print_error('auth_ldap_usertypeundefined', 'auth_ldap');
+                throw new \moodle_exception('auth_ldap_usertypeundefined', 'auth_ldap');
         }
         return $result;
     }
@@ -1474,7 +1474,7 @@ function ldap_unix2expirationtime($time) {
                 $result = $time ; // Already in correct format
                 break;
             default:
-                print_error('auth_ldap_usertypeundefined2', 'auth_ldap');
+                throw new \moodle_exception('auth_ldap_usertypeundefined2', 'auth_ldap');
         }
         return $result;
 
@@ -1999,7 +1999,7 @@ function ldap_connect() {
             return $ldapconnection;
         }
 
-        print_error('auth_ldap_noconnect_all', 'auth_ldap', '', $debuginfo);
+        throw new \moodle_exception('auth_ldap_noconnect_all', 'auth_ldap', '', $debuginfo);
     }
 
     /**
diff --git a/auth/ldap/ntlmsso_attempt.php b/auth/ldap/ntlmsso_attempt.php
index ff483a7eefb4b..6f107caba0fa1 100644
--- a/auth/ldap/ntlmsso_attempt.php
+++ b/auth/ldap/ntlmsso_attempt.php
@@ -10,12 +10,12 @@
 
 $authsequence = get_enabled_auth_plugins(); // Auths, in sequence.
 if (!in_array('ldap', $authsequence, true)) {
-    print_error('ldap_isdisabled', 'auth');
+    throw new \moodle_exception('ldap_isdisabled', 'auth');
 }
 
 $authplugin = get_auth_plugin('ldap');
 if (empty($authplugin->config->ntlmsso_enabled)) {
-    print_error('ntlmsso_isdisabled', 'auth_ldap');
+    throw new \moodle_exception('ntlmsso_isdisabled', 'auth_ldap');
 }
 
 $sesskey = sesskey();
diff --git a/auth/ldap/ntlmsso_finish.php b/auth/ldap/ntlmsso_finish.php
index 9a9c415f41071..b0d4d7373b8f5 100644
--- a/auth/ldap/ntlmsso_finish.php
+++ b/auth/ldap/ntlmsso_finish.php
@@ -10,12 +10,12 @@
 
 $authsequence = get_enabled_auth_plugins(); // Auths, in sequence.
 if (!in_array('ldap', $authsequence, true)) {
-    print_error('ldap_isdisabled', 'auth');
+    throw new \moodle_exception('ldap_isdisabled', 'auth');
 }
 
 $authplugin = get_auth_plugin('ldap');
 if (empty($authplugin->config->ntlmsso_enabled)) {
-    print_error('ntlmsso_isdisabled', 'auth_ldap');
+    throw new \moodle_exception('ntlmsso_isdisabled', 'auth_ldap');
 }
 
 // If ntlmsso_finish() succeeds, then the code never returns,
diff --git a/auth/ldap/ntlmsso_magic.php b/auth/ldap/ntlmsso_magic.php
index f8b5fcde855e9..bb1847650ef6a 100644
--- a/auth/ldap/ntlmsso_magic.php
+++ b/auth/ldap/ntlmsso_magic.php
@@ -12,12 +12,12 @@
 
 $authsequence = get_enabled_auth_plugins(); // Auths, in sequence.
 if (!in_array('ldap', $authsequence, true)) {
-    print_error('ldap_isdisabled', 'auth');
+    throw new \moodle_exception('ldap_isdisabled', 'auth');
 }
 
 $authplugin = get_auth_plugin('ldap');
 if (empty($authplugin->config->ntlmsso_enabled)) {
-    print_error('ntlmsso_isdisabled', 'auth_ldap');
+    throw new \moodle_exception('ntlmsso_isdisabled', 'auth_ldap');
 }
 
 $sesskey = required_param('sesskey', PARAM_RAW);
@@ -41,7 +41,7 @@
     fclose($handle);
     exit;
 } else {
-    print_error('ntlmsso_iwamagicnotenabled', 'auth_ldap');
+    throw new \moodle_exception('ntlmsso_iwamagicnotenabled', 'auth_ldap');
 }
 
 
diff --git a/auth/mnet/auth.php b/auth/mnet/auth.php
index d12ef16dd3c31..6816d54692912 100644
--- a/auth/mnet/auth.php
+++ b/auth/mnet/auth.php
@@ -61,7 +61,7 @@ public function auth_plugin_mnet() {
      * @return bool Authentication success or failure.
      */
     function user_login($username, $password) {
-        return false; // print_error("mnetlocal");
+        return false; // Throw moodle_exception("mnetlocal").
     }
 
     /**
@@ -152,7 +152,7 @@ function start_jump_session($mnethostid, $wantsurl, $wantsurlbackhere=false) {
         require_once $CFG->dirroot . '/mnet/xmlrpc/client.php';
 
         if (\core\session\manager::is_loggedinas()) {
-            print_error('notpermittedtojumpas', 'mnet');
+            throw new \moodle_exception('notpermittedtojumpas', 'mnet');
         }
 
         // check remote login permissions
@@ -160,12 +160,12 @@ function start_jump_session($mnethostid, $wantsurl, $wantsurlbackhere=false) {
                 or is_mnet_remote_user($USER)
                 or isguestuser()
                 or !isloggedin()) {
-            print_error('notpermittedtojump', 'mnet');
+            throw new \moodle_exception('notpermittedtojump', 'mnet');
         }
 
         // check for SSO publish permission first
         if ($this->has_service($mnethostid, 'sso_sp') == false) {
-            print_error('hostnotconfiguredforsso', 'mnet');
+            throw new \moodle_exception('hostnotconfiguredforsso', 'mnet');
         }
 
         // set RPC timeout to 30 seconds if not configured
@@ -230,7 +230,7 @@ function confirm_mnet_session($token, $remotepeer) {
 
         // verify the remote host is configured locally before attempting RPC call
         if (! $remotehost = $DB->get_record('mnet_host', array('wwwroot' => $remotepeer->wwwroot, 'deleted' => 0))) {
-            print_error('notpermittedtoland', 'mnet');
+            throw new \moodle_exception('notpermittedtoland', 'mnet');
         }
 
         // set up the RPC request
@@ -249,22 +249,23 @@ function confirm_mnet_session($token, $remotepeer) {
                 list($code, $message) = array_map('trim',explode(':', $errormessage, 2));
                 if($code == 702) {
                     $site = get_site();
-                    print_error('mnet_session_prohibited', 'mnet', $remotepeer->wwwroot, format_string($site->fullname));
+                    throw new \moodle_exception('mnet_session_prohibited', 'mnet', $remotepeer->wwwroot,
+                        format_string($site->fullname));
                     exit;
                 }
                 $message .= "ERROR $code:<br/>$errormessage<br/>";
             }
-            print_error("rpcerror", '', '', $message);
+            throw new \moodle_exception("rpcerror", '', '', $message);
         }
         unset($mnetrequest);
 
         if (empty($remoteuser) or empty($remoteuser->username)) {
-            print_error('unknownerror', 'mnet');
+            throw new \moodle_exception('unknownerror', 'mnet');
             exit;
         }
 
         if (user_not_fully_set_up($remoteuser, false)) {
-            print_error('notenoughidpinfo', 'mnet');
+            throw new \moodle_exception('notenoughidpinfo', 'mnet');
             exit;
         }
 
@@ -289,7 +290,7 @@ function confirm_mnet_session($token, $remotepeer) {
         if (empty($localuser) || ! $localuser->id) {
             /*
             if (empty($this->config->auto_add_remote_users)) {
-                print_error('nolocaluser', 'mnet');
+                throw new \moodle_exception('nolocaluser', 'mnet');
             } See MDL-21327   for why this is commented out
             */
             $remoteuser->mnethostid = $remotehost->id;
@@ -303,7 +304,8 @@ function confirm_mnet_session($token, $remotepeer) {
 
         // check sso access control list for permission first
         if (!$this->can_login_remotely($localuser->username, $remotehost->id)) {
-            print_error('sso_mnet_login_refused', 'mnet', '', array('user'=>$localuser->username, 'host'=>$remotehost->name));
+            throw new \moodle_exception('sso_mnet_login_refused', 'mnet', '',
+                array('user' => $localuser->username, 'host' => $remotehost->name));
         }
 
         $fs = get_file_storage();
diff --git a/auth/mnet/jump.php b/auth/mnet/jump.php
index 6ee75590033e0..83ad27c63832a 100644
--- a/auth/mnet/jump.php
+++ b/auth/mnet/jump.php
@@ -43,7 +43,7 @@
 }
 
 if (!is_enabled_auth('mnet')) {
-    print_error('mnetdisable');
+    throw new \moodle_exception('mnetdisable');
 }
 
 // If hostid hasn't been specified, try getting it using wwwroot
@@ -63,7 +63,7 @@
 $url      = $mnetauth->start_jump_session($hostid, $wantsurl);
 
 if (empty($url)) {
-    print_error('DEBUG: Jump session was not started correctly or blank URL returned.'); // TODO: errors
+    throw new \moodle_exception('DEBUG: Jump session was not started correctly or blank URL returned.'); // TODO: errors.
 }
 redirect($url);
 
diff --git a/auth/mnet/land.php b/auth/mnet/land.php
index 07317d1cd5b1a..3e5fceb64c1c2 100644
--- a/auth/mnet/land.php
+++ b/auth/mnet/land.php
@@ -40,7 +40,7 @@
 $site = get_site();
 
 if (!is_enabled_auth('mnet')) {
-    print_error('mnetdisable');
+    throw new \moodle_exception('mnetdisable');
 }
 
 // confirm the MNET session
diff --git a/auth/oauth2/confirm-account.php b/auth/oauth2/confirm-account.php
index 9b4a129821520..955f44939ebba 100644
--- a/auth/oauth2/confirm-account.php
+++ b/auth/oauth2/confirm-account.php
@@ -58,7 +58,7 @@
     // The user has confirmed successfully, let's log them in.
 
     if (!$user = get_complete_user_data('username', $username)) {
-        print_error('cannotfinduser', '', '', s($username));
+        throw new \moodle_exception('cannotfinduser', '', '', s($username));
     }
 
     if (!$user->suspended) {
diff --git a/auth/oauth2/confirm-linkedlogin.php b/auth/oauth2/confirm-linkedlogin.php
index a05ba2ae0c150..879655ae92bbf 100644
--- a/auth/oauth2/confirm-linkedlogin.php
+++ b/auth/oauth2/confirm-linkedlogin.php
@@ -45,7 +45,7 @@
     // The user has confirmed successfully, let's log them in.
 
     if (!$user = get_complete_user_data('id', $userid)) {
-        print_error('cannotfinduser', '', '', $userid);
+        throw new \moodle_exception('cannotfinduser', '', '', $userid);
     }
 
     if (!$user->suspended) {
diff --git a/auth/shibboleth/auth.php b/auth/shibboleth/auth.php
index 8bedda9d34cc8..f2a57a99f19f4 100644
--- a/auth/shibboleth/auth.php
+++ b/auth/shibboleth/auth.php
@@ -105,7 +105,11 @@ function get_userinfo($username) {
 
         // Check whether we have got all the essential attributes
         if ( empty($_SERVER[$this->config->user_attribute]) ) {
-            print_error( 'shib_not_all_attributes_error', 'auth_shibboleth' , '', "'".$this->config->user_attribute."' ('".$_SERVER[$this->config->user_attribute]."'), '".$this->config->field_map_firstname."' ('".$_SERVER[$this->config->field_map_firstname]."'), '".$this->config->field_map_lastname."' ('".$_SERVER[$this->config->field_map_lastname]."') and '".$this->config->field_map_email."' ('".$_SERVER[$this->config->field_map_email]."')");
+            throw new \moodle_exception( 'shib_not_all_attributes_error', 'auth_shibboleth' , '',
+                    "'".$this->config->user_attribute."' ('".$_SERVER[$this->config->user_attribute]."'), '".
+                $this->config->field_map_firstname."' ('".$_SERVER[$this->config->field_map_firstname]."'), '".
+                $this->config->field_map_lastname."' ('".$_SERVER[$this->config->field_map_lastname]."') and '".
+                $this->config->field_map_email."' ('".$_SERVER[$this->config->field_map_email]."')");
         }
 
         $attrmap = $this->get_attributes();
diff --git a/auth/shibboleth/index.php b/auth/shibboleth/index.php
index df0a7c9766871..576d332a686a3 100644
--- a/auth/shibboleth/index.php
+++ b/auth/shibboleth/index.php
@@ -34,7 +34,7 @@
     // Check whether Shibboleth is configured properly
     $readmeurl = (new moodle_url('/auth/shibboleth/README.txt'))->out();
     if (empty($pluginconfig->user_attribute)) {
-        print_error('shib_not_set_up_error', 'auth_shibboleth', '', $readmeurl);
+        throw new \moodle_exception('shib_not_set_up_error', 'auth_shibboleth', '', $readmeurl);
      }
 
 /// If we can find the Shibboleth attribute, save it in session and return to main login page
@@ -88,14 +88,16 @@
 
         else {
             // The Shibboleth user couldn't be mapped to a valid Moodle user
-            print_error('shib_invalid_account_error', 'auth_shibboleth');
+            throw new \moodle_exception('shib_invalid_account_error', 'auth_shibboleth');
         }
     }
 
     // If we can find any (user independent) Shibboleth attributes but no user
     // attributes we probably didn't receive any user attributes
     elseif (!empty($_SERVER['HTTP_SHIB_APPLICATION_ID']) || !empty($_SERVER['Shib-Application-ID'])) {
-        print_error('shib_no_attributes_error', 'auth_shibboleth' , '', '\''.$pluginconfig->user_attribute.'\', \''.$pluginconfig->field_map_firstname.'\', \''.$pluginconfig->field_map_lastname.'\' and \''.$pluginconfig->field_map_email.'\'');
+        throw new \moodle_exception('shib_no_attributes_error', 'auth_shibboleth' , '',
+            '\''.$pluginconfig->user_attribute.'\', \''.$pluginconfig->field_map_firstname.'\', \''.
+            $pluginconfig->field_map_lastname.'\' and \''.$pluginconfig->field_map_email.'\'');
     } else {
-        print_error('shib_not_set_up_error', 'auth_shibboleth', '', $readmeurl);
+        throw new \moodle_exception('shib_not_set_up_error', 'auth_shibboleth', '', $readmeurl);
     }
diff --git a/backup/backup.php b/backup/backup.php
index 12ddbe4a1aef8..364e715f5efb9 100644
--- a/backup/backup.php
+++ b/backup/backup.php
@@ -102,7 +102,7 @@
         $heading = get_string('backupactivity', 'backup', $cm->name);
         break;
     default :
-        print_error('unknownbackuptype');
+        throw new \moodle_exception('unknownbackuptype');
 }
 
 $PAGE->set_title($heading);
diff --git a/backup/import.php b/backup/import.php
index 679c29a8aa890..402a269b6fc40 100644
--- a/backup/import.php
+++ b/backup/import.php
@@ -147,7 +147,7 @@
     // backups don't store resulting files ever
     $tempdestination = make_backup_temp_directory($backupid, false);
     if (!file_exists($tempdestination) || !is_dir($tempdestination)) {
-        print_error('unknownbackupexporterror'); // shouldn't happen ever
+        throw new \moodle_exception('unknownbackupexporterror'); // Shouldn't happen ever.
     }
 
     // Prepare the restore controller. We don't need a UI here as we will just use what
diff --git a/badges/alignment.php b/badges/alignment.php
index 71c349b43e8a2..cfd4a460fa878 100644
--- a/badges/alignment.php
+++ b/badges/alignment.php
@@ -33,7 +33,7 @@
 
 require_login();
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 $badge = new badge($badgeid);
 $context = $badge->get_context();
@@ -42,7 +42,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/assertion.php b/badges/assertion.php
index 29f1d9ec82f13..b6d101cd02e4a 100644
--- a/badges/assertion.php
+++ b/badges/assertion.php
@@ -31,7 +31,7 @@
 require_once($CFG->libdir . '/badgeslib.php');
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $hash = required_param('b', PARAM_ALPHANUM); // Issued badge unique hash for badge assertion.
diff --git a/badges/award.php b/badges/award.php
index 85caa99ab9b57..b503ac19234e5 100644
--- a/badges/award.php
+++ b/badges/award.php
@@ -36,7 +36,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $badge = new badge($badgeid);
@@ -47,7 +47,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/criteria.php b/badges/criteria.php
index 72b880b246d9b..f4f6c9502111e 100644
--- a/badges/criteria.php
+++ b/badges/criteria.php
@@ -33,7 +33,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $badge = new badge($badgeid);
@@ -44,7 +44,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/criteria/award_criteria.php b/badges/criteria/award_criteria.php
index 4519d706371cb..b568df3257e6e 100644
--- a/badges/criteria/award_criteria.php
+++ b/badges/criteria/award_criteria.php
@@ -158,7 +158,7 @@ public static function build($params) {
         $types = badges_list_criteria(false);
 
         if (!isset($params['criteriatype']) || !isset($types[$params['criteriatype']])) {
-            print_error('error:invalidcriteriatype', 'badges');
+            throw new \moodle_exception('error:invalidcriteriatype', 'badges');
         }
 
         $class = 'award_criteria_' . $types[$params['criteriatype']];
diff --git a/badges/edit.php b/badges/edit.php
index 1bbc9e8a76fac..b556c69b3a84a 100644
--- a/badges/edit.php
+++ b/badges/edit.php
@@ -34,7 +34,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $badge = new badge($badgeid);
@@ -49,7 +49,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/endorsement.php b/badges/endorsement.php
index ba9b7396c21d0..c5abd12cbc9f9 100644
--- a/badges/endorsement.php
+++ b/badges/endorsement.php
@@ -31,7 +31,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $badge = new badge($badgeid);
@@ -41,7 +41,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/endorsement_json.php b/badges/endorsement_json.php
index 9ecd3ac8f029d..27796ea8c660e 100644
--- a/badges/endorsement_json.php
+++ b/badges/endorsement_json.php
@@ -28,7 +28,7 @@
 require_once($CFG->libdir . '/badgeslib.php');
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 global $DB;
diff --git a/badges/external.php b/badges/external.php
index 39850a25cacea..c9f7b3b9ab542 100644
--- a/badges/external.php
+++ b/badges/external.php
@@ -55,7 +55,7 @@
 
 // If we didn't find any badges then print an error.
 if (is_null($out)) {
-    print_error('error:externalbadgedoesntexist', 'badges');
+    throw new \moodle_exception('error:externalbadgedoesntexist', 'badges');
 }
 
 $badges = $out->badges;
@@ -73,7 +73,7 @@
 
 // If we didn't find the badge a user might be trying to replace the userid parameter.
 if (empty($badge)) {
-    print_error('error:externalbadgedoesntexist', 'badges');
+    throw new \moodle_exception('error:externalbadgedoesntexist', 'badges');
 }
 
 $output = $PAGE->get_renderer('core', 'badges');
diff --git a/badges/image_author_json.php b/badges/image_author_json.php
index 1cfb92e9e7efa..50438dcdc1714 100644
--- a/badges/image_author_json.php
+++ b/badges/image_author_json.php
@@ -29,7 +29,7 @@
 require_once($CFG->libdir . '/badgeslib.php');
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $id = required_param('id', PARAM_INT); // Unique hash of badge assertion.
diff --git a/badges/index.php b/badges/index.php
index 7b420ba840bdb..772fa0e9752ef 100644
--- a/badges/index.php
+++ b/badges/index.php
@@ -53,11 +53,11 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 if (empty($CFG->badges_allowcoursebadges) && ($type == BADGE_TYPE_COURSE)) {
-    print_error('coursebadgesdisabled', 'badges');
+    throw new \moodle_exception('coursebadgesdisabled', 'badges');
 }
 
 $err = '';
diff --git a/badges/mybackpack.php b/badges/mybackpack.php
index 89c3ffdba4d36..4220f5eaf9a58 100644
--- a/badges/mybackpack.php
+++ b/badges/mybackpack.php
@@ -30,7 +30,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $context = context_user::instance($USER->id);
@@ -145,7 +145,7 @@
                         get_string('backpackemailverifypending', 'badges', $data->backpackemail),
                         null, \core\output\notification::NOTIFY_INFO);
                 } else {
-                    print_error ('backpackcannotsendverification', 'badges');
+                    throw new \moodle_exception('backpackcannotsendverification', 'badges');
                 }
             }
         }
diff --git a/badges/mybadges.php b/badges/mybadges.php
index 42f285ea8c798..b9312f701719e 100644
--- a/badges/mybadges.php
+++ b/badges/mybadges.php
@@ -40,7 +40,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $url = new moodle_url('/badges/mybadges.php');
diff --git a/badges/newbadge.php b/badges/newbadge.php
index b49aff5d11338..d6bbbcdee5fa3 100644
--- a/badges/newbadge.php
+++ b/badges/newbadge.php
@@ -33,11 +33,11 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 if (empty($CFG->badges_allowcoursebadges) && ($type == BADGE_TYPE_COURSE)) {
-    print_error('coursebadgesdisabled', 'badges');
+    throw new \moodle_exception('coursebadgesdisabled', 'badges');
 }
 
 $title = get_string('create', 'badges');
diff --git a/badges/overview.php b/badges/overview.php
index 52f8949fb45aa..dbf814fc7788e 100644
--- a/badges/overview.php
+++ b/badges/overview.php
@@ -33,7 +33,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $badge = new badge($badgeid);
@@ -42,7 +42,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/preferences.php b/badges/preferences.php
index 7e01e2c5f2acb..834386656c408 100644
--- a/badges/preferences.php
+++ b/badges/preferences.php
@@ -36,7 +36,7 @@
 $PAGE->set_pagelayout('standard');
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $mform = new badges_preferences_form();
diff --git a/badges/recipients.php b/badges/recipients.php
index 623d8e64cf464..8a29747e67343 100644
--- a/badges/recipients.php
+++ b/badges/recipients.php
@@ -35,7 +35,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 if (!in_array($sortby, array('firstname', 'lastname', 'dateissued'))) {
@@ -56,7 +56,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/related.php b/badges/related.php
index f817cf6af4fc7..37beb69593e7c 100644
--- a/badges/related.php
+++ b/badges/related.php
@@ -35,7 +35,7 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 $badge = new badge($badgeid);
@@ -45,7 +45,7 @@
 
 if ($badge->type == BADGE_TYPE_COURSE) {
     if (empty($CFG->badges_allowcoursebadges)) {
-        print_error('coursebadgesdisabled', 'badges');
+        throw new \moodle_exception('coursebadgesdisabled', 'badges');
     }
     require_login($badge->courseid);
     $course = get_course($badge->courseid);
diff --git a/badges/view.php b/badges/view.php
index 527e904d7f250..eabf3b92fc3be 100644
--- a/badges/view.php
+++ b/badges/view.php
@@ -36,11 +36,11 @@
 require_login();
 
 if (empty($CFG->enablebadges)) {
-    print_error('badgesdisabled', 'badges');
+    throw new \moodle_exception('badgesdisabled', 'badges');
 }
 
 if (empty($CFG->badges_allowcoursebadges) && $courseid != 0) {
-    print_error('coursebadgesdisabled', 'badges');
+    throw new \moodle_exception('coursebadgesdisabled', 'badges');
 }
 
 if (!in_array($sortby, array('name', 'dateissued'))) {
diff --git a/blocks/admin_bookmarks/create.php b/blocks/admin_bookmarks/create.php
index 07ed88f860328..aadcaa48a6fd5 100644
--- a/blocks/admin_bookmarks/create.php
+++ b/blocks/admin_bookmarks/create.php
@@ -37,7 +37,7 @@
         $bookmarks = explode(',', get_user_preferences('admin_bookmarks'));
 
         if (in_array($section, $bookmarks)) {
-            print_error('bookmarkalreadyexists','admin');
+            throw new \moodle_exception('bookmarkalreadyexists', 'admin');
             die;
         }
 
@@ -53,7 +53,7 @@
         set_user_preference('admin_bookmarks', $bookmarks);
 
     } else {
-        print_error('invalidsection','admin');
+        throw new \moodle_exception('invalidsection', 'admin');
         die;
     }
 
@@ -69,7 +69,7 @@
     }
 
 } else {
-    print_error('invalidsection','admin');
+    throw new \moodle_exception('invalidsection', 'admin');
     die;
 }
 
diff --git a/blocks/admin_bookmarks/delete.php b/blocks/admin_bookmarks/delete.php
index a1d8f14ebab19..9343ad26a7f60 100644
--- a/blocks/admin_bookmarks/delete.php
+++ b/blocks/admin_bookmarks/delete.php
@@ -41,7 +41,7 @@
         $key = array_search($section, $bookmarks);
 
         if ($key === false) {
-            print_error('nonexistentbookmark','admin');
+            throw new \moodle_exception('nonexistentbookmark', 'admin');
             die;
         }
 
@@ -65,11 +65,11 @@
 
     }
 
-    print_error('nobookmarksforuser','admin');
+    throw new \moodle_exception('nobookmarksforuser', 'admin');
     die;
 
 } else {
-    print_error('invalidsection', 'admin');
+    throw new \moodle_exception('invalidsection', 'admin');
     die;
 }
 
diff --git a/blocks/completionstatus/details.php b/blocks/completionstatus/details.php
index 33bbe775f85f4..830275fc76ebb 100644
--- a/blocks/completionstatus/details.php
+++ b/blocks/completionstatus/details.php
@@ -44,7 +44,7 @@
 require_login();
 
 if (!completion_can_view_data($user->id, $course)) {
-    print_error('cannotviewreport');
+    throw new \moodle_exception('cannotviewreport');
 }
 
 // Load completion data.
@@ -54,15 +54,15 @@
 
 // Don't display if completion isn't enabled.
 if (!$info->is_enabled()) {
-    print_error('completionnotenabled', 'completion', $returnurl);
+    throw new \moodle_exception('completionnotenabled', 'completion', $returnurl);
 }
 
 // Check this user is enroled.
 if (!$info->is_tracked_user($user->id)) {
     if ($USER->id == $user->id) {
-        print_error('notenroled', 'completion', $returnurl);
+        throw new \moodle_exception('notenroled', 'completion', $returnurl);
     } else {
-        print_error('usernotenroled', 'completion', $returnurl);
+        throw new \moodle_exception('usernotenroled', 'completion', $returnurl);
     }
 }
 
diff --git a/blocks/rss_client/viewfeed.php b/blocks/rss_client/viewfeed.php
index c56eb30a9202e..dc993bb18161b 100644
--- a/blocks/rss_client/viewfeed.php
+++ b/blocks/rss_client/viewfeed.php
@@ -27,7 +27,7 @@
 
 require_login();
 if (isguestuser()) {
-    print_error('guestsarenotallowed');
+    throw new \moodle_exception('guestsarenotallowed');
 }
 
 $returnurl = optional_param('returnurl', '', PARAM_LOCALURL);
@@ -62,7 +62,7 @@
 
 if ($rss->error()) {
     debugging($rss->error());
-    print_error('errorfetchingrssfeed');
+    throw new \moodle_exception('errorfetchingrssfeed');
 }
 
 $strviewfeed = get_string('viewfeed', 'block_rss_client');
diff --git a/blog/edit.php b/blog/edit.php
index bf9a166626910..435445d748764 100644
--- a/blog/edit.php
+++ b/blog/edit.php
@@ -55,7 +55,7 @@
 
 if ($id) {
     if (!$entry = new blog_entry($id)) {
-        print_error('wrongentryid', 'blog');
+        throw new \moodle_exception('wrongentryid', 'blog');
     }
     $userid = $entry->userid;
 } else {
@@ -75,11 +75,11 @@
 require_login($courseid);
 
 if (empty($CFG->enableblogs)) {
-    print_error('blogdisable', 'blog');
+    throw new \moodle_exception('blogdisable', 'blog');
 }
 
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 $returnurl = new moodle_url('/blog/index.php');
@@ -98,19 +98,19 @@
 $blogheaders = blog_get_headers();
 
 if (!has_capability('moodle/blog:create', $sitecontext) && !has_capability('moodle/blog:manageentries', $sitecontext)) {
-    print_error('cannoteditentryorblog');
+    throw new \moodle_exception('cannoteditentryorblog');
 }
 
 // Make sure that the person trying to edit has access right.
 if ($id) {
     if (!blog_user_can_edit_entry($entry)) {
-        print_error('notallowedtoedit', 'blog');
+        throw new \moodle_exception('notallowedtoedit', 'blog');
     }
     $entry->subject      = clean_text($entry->subject);
     $entry->summary      = clean_text($entry->summary, $entry->format);
 } else {
     if (!has_capability('moodle/blog:create', $sitecontext)) {
-        print_error('noentry', 'blog'); // The capability "manageentries" is not enough for adding.
+        throw new \moodle_exception('noentry', 'blog'); // The capability "manageentries" is not enough for adding.
     }
 }
 $returnurl->param('userid', $userid);
@@ -125,12 +125,12 @@
     comment::init();
 
     if (empty($entry->id)) {
-        print_error('wrongentryid', 'blog');
+        throw new \moodle_exception('wrongentryid', 'blog');
     }
     if (data_submitted() && $confirm && confirm_sesskey()) {
         // Make sure the current user is the author of the blog entry, or has some deleteanyentry capability.
         if (!blog_user_can_edit_entry($entry)) {
-            print_error('nopermissionstodeleteentry', 'blog');
+            throw new \moodle_exception('nopermissionstodeleteentry', 'blog');
         } else {
             $entry->delete();
             blog_rss_delete_file($userid);
@@ -232,14 +232,14 @@
 
         case 'edit':
             if (empty($entry->id)) {
-                print_error('wrongentryid', 'blog');
+                throw new \moodle_exception('wrongentryid', 'blog');
             }
 
             $entry->edit($data, $blogeditform, $summaryoptions, $attachmentoptions);
         break;
 
         default :
-            print_error('invalidaction');
+            throw new \moodle_exception('invalidaction');
     }
 
     redirect($returnurl);
@@ -272,14 +272,14 @@
 
     case 'edit':
         if (empty($entry->id)) {
-            print_error('wrongentryid', 'blog');
+            throw new \moodle_exception('wrongentryid', 'blog');
         }
         $strformheading = get_string('updateentrywithid', 'blog');
 
         break;
 
     default :
-        print_error('unknowaction');
+        throw new \moodle_exception('unknowaction');
 }
 
 $entry->modid = $modid;
diff --git a/blog/external_blog_edit.php b/blog/external_blog_edit.php
index a1a56f1e2e2e5..37fb2a5ce5214 100644
--- a/blog/external_blog_edit.php
+++ b/blog/external_blog_edit.php
@@ -55,7 +55,7 @@
 // Retrieve the external blog record.
 if (!empty($id)) {
     if (!$external = $DB->get_record('blog_external', array('id' => $id, 'userid' => $USER->id))) {
-        print_error('wrongexternalid', 'blog');
+        throw new \moodle_exception('wrongexternalid', 'blog');
     }
     $external->autotags = core_tag_tag::get_item_tags_array('core', 'blog_external', $id);
 }
@@ -122,13 +122,13 @@
                 core_tag_tag::set_item_tags('core', 'blog_external', $external->id,
                         context_user::instance($external->userid), $data->autotags);
             } else {
-                print_error('wrongexternalid', 'blog');
+                throw new \moodle_exception('wrongexternalid', 'blog');
             }
 
             break;
 
         default :
-            print_error('invalidaction');
+            throw new \moodle_exception('invalidaction');
     }
 
     redirect($returnurl);
diff --git a/blog/index.php b/blog/index.php
index f8445c08ad202..b3a11a2bc8707 100644
--- a/blog/index.php
+++ b/blog/index.php
@@ -90,7 +90,7 @@
     require_login();
     if (isguestuser()) {
         // They must have entered the url manually.
-        print_error('noguest');
+        throw new \moodle_exception('noguest');
     }
 
 } else if ($CFG->bloglevel == BLOG_USER_LEVEL) {
@@ -99,11 +99,11 @@
 
 } else {
     // Weird!
-    print_error('blogdisable', 'blog');
+    throw new \moodle_exception('blogdisable', 'blog');
 }
 
 if (empty($CFG->enableblogs)) {
-    print_error('blogdisable', 'blog');
+    throw new \moodle_exception('blogdisable', 'blog');
 }
 
 list($courseid, $userid) = blog_validate_access($courseid, $modid, $groupid, $entryid, $userid);
diff --git a/blog/lib.php b/blog/lib.php
index f575ff75ac6b9..d8825741307da 100644
--- a/blog/lib.php
+++ b/blog/lib.php
@@ -1204,7 +1204,7 @@ function blog_validate_access($courseid, $modid, $groupid, $entryid, $userid) {
     if (!$userid && has_capability('moodle/blog:view', $sitecontext) && $CFG->bloglevel > BLOG_USER_LEVEL) {
         if ($entryid) {
             if (!$entryobject = $DB->get_record('post', array('id' => $entryid))) {
-                print_error('nosuchentry', 'blog');
+                throw new \moodle_exception('nosuchentry', 'blog');
             }
             $userid = $entryobject->userid;
         }
@@ -1214,20 +1214,20 @@ function blog_validate_access($courseid, $modid, $groupid, $entryid, $userid) {
 
     if (!empty($modid)) {
         if ($CFG->bloglevel < BLOG_SITE_LEVEL) {
-            print_error(get_string('nocourseblogs', 'blog'));
+            throw new \moodle_exception('courseblogdisable', 'blog');
         }
         if (!$mod = $DB->get_record('course_modules', array('id' => $modid))) {
-            print_error(get_string('invalidmodid', 'blog'));
+            throw new \moodle_exception('invalidmoduleid', 'error', $modid);
         }
         $courseid = $mod->course;
     }
 
     if ((empty($courseid) ? true : $courseid == SITEID) && empty($userid)) {
         if ($CFG->bloglevel < BLOG_SITE_LEVEL) {
-            print_error('siteblogdisable', 'blog');
+            throw new \moodle_exception('siteblogdisable', 'blog');
         }
         if (!has_capability('moodle/blog:view', $sitecontext)) {
-            print_error('cannotviewsiteblog', 'blog');
+            throw new \moodle_exception('cannotviewsiteblog', 'blog');
         }
 
         $COURSE = $DB->get_record('course', array('format' => 'site'));
@@ -1236,13 +1236,13 @@ function blog_validate_access($courseid, $modid, $groupid, $entryid, $userid) {
 
     if (!empty($courseid)) {
         if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-            print_error('invalidcourseid');
+            throw new \moodle_exception('invalidcourseid');
         }
 
         $courseid = $course->id;
 
         if (!has_capability('moodle/blog:view', $sitecontext)) {
-            print_error('cannotviewcourseblog', 'blog');
+            throw new \moodle_exception('cannotviewcourseblog', 'blog');
         }
     } else {
         $coursecontext = context_course::instance(SITEID);
@@ -1250,54 +1250,54 @@ function blog_validate_access($courseid, $modid, $groupid, $entryid, $userid) {
 
     if (!empty($groupid)) {
         if ($CFG->bloglevel < BLOG_SITE_LEVEL) {
-            print_error('groupblogdisable', 'blog');
+            throw new \moodle_exception('groupblogdisable', 'blog');
         }
 
         if (! $group = groups_get_group($groupid)) {
-            print_error(get_string('invalidgroupid', 'blog'));
+            throw new \moodle_exception('invalidgroupid', 'blog');
         }
 
         if (!$course = $DB->get_record('course', array('id' => $group->courseid))) {
-            print_error('invalidcourseid');
+            throw new \moodle_exception('invalidcourseid');
         }
 
         $coursecontext = context_course::instance($course->id);
         $courseid = $course->id;
 
         if (!has_capability('moodle/blog:view', $sitecontext)) {
-            print_error(get_string('cannotviewcourseorgroupblog', 'blog'));
+            throw new \moodle_exception('cannotviewcourseorgroupblog', 'blog');
         }
 
         if (groups_get_course_groupmode($course) == SEPARATEGROUPS &&
                 !has_capability('moodle/site:accessallgroups', $coursecontext)) {
 
             if (!groups_is_member($groupid)) {
-                print_error('notmemberofgroup');
+                throw new \moodle_exception('notmemberofgroup');
             }
         }
     }
 
     if (!empty($userid)) {
         if ($CFG->bloglevel < BLOG_USER_LEVEL) {
-            print_error('blogdisable', 'blog');
+            throw new \moodle_exception('blogdisable', 'blog');
         }
 
         if (!$user = $DB->get_record('user', array('id' => $userid))) {
-            print_error('invaliduserid');
+            throw new \moodle_exception('invaliduserid');
         }
 
         if ($user->deleted) {
-            print_error('userdeleted');
+            throw new \moodle_exception('userdeleted');
         }
 
         if ($USER->id == $userid) {
             if (!has_capability('moodle/blog:create', $sitecontext)
               && !has_capability('moodle/blog:view', $sitecontext)) {
-                print_error('donothaveblog', 'blog');
+                throw new \moodle_exception('donothaveblog', 'blog');
             }
         } else {
             if (!has_capability('moodle/blog:view', $sitecontext) || !blog_user_can_view_user_entry($userid)) {
-                print_error('cannotviewcourseblog', 'blog');
+                throw new \moodle_exception('cannotviewcourseblog', 'blog');
             }
         }
     }
diff --git a/blog/preferences.php b/blog/preferences.php
index cd89980dd5dd0..c950f3792552a 100644
--- a/blog/preferences.php
+++ b/blog/preferences.php
@@ -61,11 +61,11 @@
 require_login($courseid);
 
 if (empty($CFG->enableblogs)) {
-    print_error('blogdisable', 'blog');
+    throw new \moodle_exception('blogdisable', 'blog');
 }
 
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 // The preference is site wide not blog specific. Hence user should have permissions in site level.
@@ -80,7 +80,7 @@
     $pagesize = $data->pagesize;
 
     if ($pagesize < 1) {
-        print_error('invalidpagesize');
+        throw new \moodle_exception('invalidpagesize');
     }
     useredit_update_user_preference(['id' => $USER->id,
         'preference_blogpagesize' => $pagesize]);
diff --git a/cache/classes/local/administration_display_helper.php b/cache/classes/local/administration_display_helper.php
index 949a3c1b2ebb7..e2c709e0deaed 100644
--- a/cache/classes/local/administration_display_helper.php
+++ b/cache/classes/local/administration_display_helper.php
@@ -444,7 +444,7 @@ public function action_addstore() : array {
 
         $plugin = required_param('plugin', PARAM_PLUGIN);
         if (!$storepluginsummaries[$plugin]['canaddinstance']) {
-            print_error('ex_unmetstorerequirements', 'cache');
+            throw new \moodle_exception('ex_unmetstorerequirements', 'cache');
         }
         $mform = $this->get_add_store_form($plugin);
         $title = get_string('addstore', 'cache', $storepluginsummaries[$plugin]['name']);
diff --git a/calendar/classes/local/event/forms/create.php b/calendar/classes/local/event/forms/create.php
index 7775e45860f3b..c874d6996e8d3 100644
--- a/calendar/classes/local/event/forms/create.php
+++ b/calendar/classes/local/event/forms/create.php
@@ -71,7 +71,7 @@ public function definition() {
         $eventtypes = $this->_customdata['eventtypes'];
 
         if (in_array(true, $eventtypes, true) === false) {
-            print_error('nopermissiontoupdatecalendar');
+            throw new \moodle_exception('nopermissiontoupdatecalendar');
         }
 
         $mform->setDisableShortforms();
diff --git a/calendar/classes/local/event/forms/managesubscriptions.php b/calendar/classes/local/event/forms/managesubscriptions.php
index 5011f59e30dad..b228914e087b4 100644
--- a/calendar/classes/local/event/forms/managesubscriptions.php
+++ b/calendar/classes/local/event/forms/managesubscriptions.php
@@ -44,7 +44,7 @@ public function definition() {
         $mform = $this->_form;
         $eventtypes = calendar_get_allowed_event_types();
         if (in_array(true, $eventtypes, true) === false) {
-            print_error('nopermissiontoupdatecalendar');
+            throw new \moodle_exception('nopermissiontoupdatecalendar');
         }
 
         // Name.
diff --git a/calendar/delete.php b/calendar/delete.php
index b27fea73b525d..28af3809c997a 100644
--- a/calendar/delete.php
+++ b/calendar/delete.php
@@ -60,7 +60,7 @@
 $title = get_string('deleteevent', 'calendar');
 // Check the user has the required capabilities to delete an event
 if (!calendar_delete_event_allowed($event)) {
-    print_error('nopermissions', 'error', $PAGE->url, $title);
+    throw new \moodle_exception('nopermissions', 'error', $PAGE->url, $title);
 }
 
 // Count the repeats, do we need to consider the possibility of deleting repeats
@@ -75,7 +75,7 @@
 if ($confirm) {
     // Confirm the session key to stop CSRF
     if (!confirm_sesskey()) {
-        print_error('confirmsesskeybad');
+        throw new \moodle_exception('confirmsesskeybad');
     }
     // Delete the event and possibly repeats
     $event->delete($repeats);
diff --git a/calendar/event.php b/calendar/event.php
index f804b7f19a7d4..425dfb9f7ed99 100644
--- a/calendar/event.php
+++ b/calendar/event.php
@@ -115,7 +115,7 @@
     $title = get_string('editevent', 'calendar');
     $event = calendar_event::load($eventid);
     if (!calendar_edit_event_allowed($event, true)) {
-        print_error('nopermissions');
+        throw new \moodle_exception('nopermissions');
     }
     $event->action = $action;
     $event->course = $courseid;
@@ -123,7 +123,7 @@
     $event->count_repeats();
 
     if (!calendar_add_event_allowed($event)) {
-        print_error('nopermissions');
+        throw new \moodle_exception('nopermissions');
     }
 
     // Check to see if this event is part of a subscription or import.
@@ -151,7 +151,7 @@
     $event->timestart = $time;
     $event = new calendar_event($event);
     if (!calendar_add_event_allowed($event)) {
-        print_error('nopermissions');
+        throw new \moodle_exception('nopermissions');
     }
 }
 
diff --git a/calendar/externallib.php b/calendar/externallib.php
index 46206adfe7cd9..d8eb9b60cb3a2 100644
--- a/calendar/externallib.php
+++ b/calendar/externallib.php
@@ -934,7 +934,7 @@ public static function submit_create_update_form($formdata) {
             }
 
             if (!calendar_edit_event_allowed($legacyevent, true)) {
-                print_error('nopermissiontoupdatecalendar');
+                throw new \moodle_exception('nopermissiontoupdatecalendar');
             }
 
             $legacyevent->update($properties);
@@ -1192,7 +1192,7 @@ public static function update_event_start_day($eventid, $daytimestamp) {
         $legacyevent = $mapper->from_event_to_legacy_event($event);
 
         if (!calendar_edit_event_allowed($legacyevent, true)) {
-            print_error('nopermissiontoupdatecalendar');
+            throw new \moodle_exception('nopermissiontoupdatecalendar');
         }
 
         self::validate_context($legacyevent->context);
diff --git a/calendar/lib.php b/calendar/lib.php
index 9bba24d5e2e06..2edb40fa6a30a 100644
--- a/calendar/lib.php
+++ b/calendar/lib.php
@@ -478,7 +478,7 @@ public function update($data, $checkcapability=true) {
         if (empty($this->properties->id) || $this->properties->id < 1) {
             if ($checkcapability) {
                 if (!calendar_add_event_allowed($this->properties)) {
-                    print_error('nopermissiontoupdatecalendar');
+                    throw new \moodle_exception('nopermissiontoupdatecalendar');
                 }
             }
 
@@ -594,7 +594,7 @@ public function update($data, $checkcapability=true) {
 
             if ($checkcapability) {
                 if (!calendar_edit_event_allowed($this->properties)) {
-                    print_error('nopermissiontoupdatecalendar');
+                    throw new \moodle_exception('nopermissiontoupdatecalendar');
                 }
             }
 
@@ -810,7 +810,7 @@ public function properties($prepareeditor = false) {
                     // First check the course is valid.
                     $course = $DB->get_record('course', array('id' => $properties->courseid));
                     if (!$course) {
-                        print_error('invalidcourse');
+                        throw new \moodle_exception('invalidcourse');
                     }
                     // Course context.
                     $this->editorcontext = $this->get_context();
@@ -2875,7 +2875,7 @@ function calendar_add_subscription($sub) {
             return $sub->id;
         }
     } else {
-        print_error('errorbadsubscription', 'importcalendar');
+        throw new \moodle_exception('errorbadsubscription', 'importcalendar');
     }
 }
 
@@ -3619,7 +3619,7 @@ function calendar_output_fragment_event_form($args) {
         $event = calendar_event::load($eventid);
 
         if (!calendar_edit_event_allowed($event)) {
-            print_error('nopermissiontoupdatecalendar');
+            throw new \moodle_exception('nopermissiontoupdatecalendar');
         }
 
         $mapper = new \core_calendar\local\event\mappers\create_update_form_mapper();
diff --git a/calendar/managesubscriptions.php b/calendar/managesubscriptions.php
index 4cf8854fa97f4..c4c41ea449c87 100644
--- a/calendar/managesubscriptions.php
+++ b/calendar/managesubscriptions.php
@@ -66,7 +66,7 @@
 require_login($course, false);
 
 if (!calendar_user_can_add_event($course)) {
-    print_error('errorcannotimport', 'calendar');
+    throw new \moodle_exception('errorcannotimport', 'calendar');
 }
 $PAGE->navbar->add(get_string('managesubscriptions', 'calendar'), $PAGE->url);
 
diff --git a/cohort/edit.php b/cohort/edit.php
index fe98535e5f25b..ff03dde09d793 100644
--- a/cohort/edit.php
+++ b/cohort/edit.php
@@ -44,7 +44,7 @@
 } else {
     $context = context::instance_by_id($contextid, MUST_EXIST);
     if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
-        print_error('invalidcontext');
+        throw new \moodle_exception('invalidcontext');
     }
     $cohort = new stdClass();
     $cohort->id          = 0;
diff --git a/cohort/index.php b/cohort/index.php
index a3ce8f6e00a08..c726d29598282 100644
--- a/cohort/index.php
+++ b/cohort/index.php
@@ -40,7 +40,7 @@
 }
 
 if ($context->contextlevel != CONTEXT_COURSECAT and $context->contextlevel != CONTEXT_SYSTEM) {
-    print_error('invalidcontext');
+    throw new \moodle_exception('invalidcontext');
 }
 
 $category = null;
diff --git a/cohort/upload.php b/cohort/upload.php
index cc1372f959a52..a9a857e07123d 100644
--- a/cohort/upload.php
+++ b/cohort/upload.php
@@ -37,7 +37,7 @@
     $context = context_system::instance();
 }
 if ($context->contextlevel != CONTEXT_COURSECAT && $context->contextlevel != CONTEXT_SYSTEM) {
-    print_error('invalidcontext');
+    throw new \moodle_exception('invalidcontext');
 }
 
 require_capability('moodle/cohort:manage', $context);
diff --git a/comment/index.php b/comment/index.php
index 77c383a9871a0..8d4bd59cca54e 100644
--- a/comment/index.php
+++ b/comment/index.php
@@ -77,7 +77,7 @@
 echo $OUTPUT->heading(get_string('comments'));
 echo $OUTPUT->box_start('generalbox commentsreport');
 if (!empty($err)) {
-    print_error($err, 'error', $CFG->wwwroot.'/comment/');
+    throw new \moodle_exception($err, 'error', $CFG->wwwroot.'/comment/');
 }
 if (empty($action)) {
     echo '<form method="post">';
diff --git a/comment/lib.php b/comment/lib.php
index 4f62b149918d6..b1074f31b21c5 100644
--- a/comment/lib.php
+++ b/comment/lib.php
@@ -135,7 +135,7 @@ public function __construct(stdClass $options) {
             $this->contextid = $options->contextid;
             $this->context = context::instance_by_id($this->contextid);
         } else {
-            print_error('invalidcontext');
+            throw new \moodle_exception('invalidcontext');
         }
 
         if (!empty($options->component)) {
diff --git a/completion/classes/bulkedit_form.php b/completion/classes/bulkedit_form.php
index 0e6159aee3c75..d17ae8ab76d78 100644
--- a/completion/classes/bulkedit_form.php
+++ b/completion/classes/bulkedit_form.php
@@ -73,7 +73,7 @@ protected function get_module_form() {
         if (file_exists($modmoodleform)) {
             require_once($modmoodleform);
         } else {
-            print_error('noformdesc');
+            throw new \moodle_exception('noformdesc');
         }
 
         list($cmrec, $context, $module, $data, $cw) = get_moduleinfo_data($cm, $course);
diff --git a/completion/classes/defaultedit_form.php b/completion/classes/defaultedit_form.php
index 71ce1e1b80cff..7880a727a064a 100644
--- a/completion/classes/defaultedit_form.php
+++ b/completion/classes/defaultedit_form.php
@@ -73,7 +73,7 @@ protected function get_module_form() {
         if (file_exists($modmoodleform)) {
             require_once($modmoodleform);
         } else {
-            print_error('noformdesc');
+            throw new \moodle_exception('noformdesc');
         }
 
         list($module, $context, $cw, $cmrec, $data) = prepare_new_moduleinfo_data($course, $modname, 0);
diff --git a/completion/criteria/completion_criteria.php b/completion/criteria/completion_criteria.php
index baa3977ead30f..16443835b29dd 100644
--- a/completion/criteria/completion_criteria.php
+++ b/completion/criteria/completion_criteria.php
@@ -170,7 +170,7 @@ public static function factory($params) {
         global $CFG, $COMPLETION_CRITERIA_TYPES;
 
         if (!isset($params['criteriatype']) || !isset($COMPLETION_CRITERIA_TYPES[$params['criteriatype']])) {
-            print_error('invalidcriteriatype', 'completion');
+            throw new \moodle_exception('invalidcriteriatype', 'completion');
         }
 
         $class = 'completion_criteria_'.$COMPLETION_CRITERIA_TYPES[$params['criteriatype']];
diff --git a/completion/data_object.php b/completion/data_object.php
index 73837ad2a423f..515fef7a008f1 100644
--- a/completion/data_object.php
+++ b/completion/data_object.php
@@ -188,7 +188,7 @@ protected static function fetch_helper($table, $classname, $params) {
         if ($instances = self::fetch_all_helper($table, $classname, $params)) {
             if (count($instances) > 1) {
                 // we should not tolerate any errors here - problems might appear later
-                print_error('morethanonerecordinfetch','debug');
+                throw new \moodle_exception('morethanonerecordinfetch', 'debug');
             }
             return reset($instances);
         } else {
diff --git a/contentbank/contenttype/h5p/classes/form/editor.php b/contentbank/contenttype/h5p/classes/form/editor.php
index 26dc2d360d6a3..0a6c9ea211b68 100644
--- a/contentbank/contenttype/h5p/classes/form/editor.php
+++ b/contentbank/contenttype/h5p/classes/form/editor.php
@@ -64,7 +64,7 @@ protected function definition() {
 
         if (empty($id) && empty($library)) {
             $returnurl = new \moodle_url('/contentbank/index.php', ['contextid' => $this->_customdata['contextid']]);
-            print_error('invalidcontentid', 'error', $returnurl);
+            throw new \moodle_exception('invalidcontentid', 'error', $returnurl);
         }
 
         $this->h5peditor = new h5peditor();
diff --git a/contentbank/edit.php b/contentbank/edit.php
index 7830afb7f2eea..db54dc35ea7ce 100644
--- a/contentbank/edit.php
+++ b/contentbank/edit.php
@@ -35,7 +35,7 @@
 
 $cb = new \core_contentbank\contentbank();
 if (!$cb->is_context_allowed($context)) {
-    print_error('contextnotallowed', 'core_contentbank');
+    throw new \moodle_exception('contextnotallowed', 'core_contentbank');
 }
 
 require_capability('moodle/contentbank:access', $context);
@@ -61,7 +61,7 @@
 // Check plugin is enabled.
 $plugin = core_plugin_manager::instance()->get_plugin_info($contenttypename);
 if (!$plugin || !$plugin->is_enabled()) {
-    print_error('unsupported', 'core_contentbank', $returnurl);
+    throw new \moodle_exception('unsupported', 'core_contentbank', $returnurl);
 }
 
 // Create content type instance.
@@ -69,12 +69,12 @@
 if (class_exists($contenttypeclass)) {
     $contenttype = new $contenttypeclass($context);
 } else {
-    print_error('unsupported', 'core_contentbank', $returnurl);
+    throw new \moodle_exception('unsupported', 'core_contentbank', $returnurl);
 }
 
 // Checks the user can edit this content and content type.
 if (!$contenttype->can_edit($content)) {
-    print_error('contenttypenoedit', 'core_contentbank', $returnurl);
+    throw new \moodle_exception('contenttypenoedit', 'core_contentbank', $returnurl);
 }
 
 $values = [
@@ -112,7 +112,7 @@
 // Instantiate the content type form.
 $editorclass = "$contenttypename\\form\\editor";
 if (!class_exists($editorclass)) {
-    print_error('noformdesc');
+    throw new \moodle_exception('noformdesc');
 }
 
 $editorform = new $editorclass(null, $values);
diff --git a/contentbank/index.php b/contentbank/index.php
index 107cb4aa82134..8dfe2907b1f88 100644
--- a/contentbank/index.php
+++ b/contentbank/index.php
@@ -32,7 +32,7 @@
 
 $cb = new \core_contentbank\contentbank();
 if (!$cb->is_context_allowed($context)) {
-    print_error('contextnotallowed', 'core_contentbank');
+    throw new \moodle_exception('contextnotallowed', 'core_contentbank');
 }
 
 require_capability('moodle/contentbank:access', $context);
diff --git a/contentbank/view.php b/contentbank/view.php
index 6bee490909837..2b9e360352d6f 100644
--- a/contentbank/view.php
+++ b/contentbank/view.php
@@ -43,7 +43,7 @@
 $returnurl = new \moodle_url('/contentbank/index.php', ['contextid' => $context->id]);
 $plugin = core_plugin_manager::instance()->get_plugin_info($record->contenttype);
 if (!$plugin || !$plugin->is_enabled()) {
-    print_error('unsupported', 'core_contentbank', $returnurl);
+    throw new \moodle_exception('unsupported', 'core_contentbank', $returnurl);
 }
 
 $title = get_string('contentbank');
@@ -94,7 +94,7 @@
                 $visibilitymsg = get_string('unlisted', 'core_contentbank');
                 break;
             default:
-                print_error('contentvisibilitynotfound', 'error', $returnurl, $content->get_visibility());
+                throw new \moodle_exception('contentvisibilitynotfound', 'error', $returnurl, $content->get_visibility());
                 break;
         }
         $statusmsg = get_string($statusmsg, 'core_contentbank', $visibilitymsg);
diff --git a/course/bulkcompletion.php b/course/bulkcompletion.php
index 2f1534d1995f8..4d84af9286338 100644
--- a/course/bulkcompletion.php
+++ b/course/bulkcompletion.php
@@ -35,17 +35,17 @@
 
     if ($id == SITEID) {
         // Don't allow editing of 'site course' using this form.
-        print_error('cannoteditsiteform');
+        throw new \moodle_exception('cannoteditsiteform');
     }
 
     if (!$course = $DB->get_record('course', array('id' => $id))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     require_login($course);
 
 } else {
     require_login();
-    print_error('needcourseid');
+    throw new \moodle_exception('needcourseid');
 }
 
 // Set up the page.
diff --git a/course/classes/deletecategory_form.php b/course/classes/deletecategory_form.php
index 906837e505d0b..713d9c4b8ac43 100644
--- a/course/classes/deletecategory_form.php
+++ b/course/classes/deletecategory_form.php
@@ -67,7 +67,7 @@ public function definition() {
             $options[1] = get_string('deleteallcannotundo');
         }
         if (empty($options)) {
-            print_error('youcannotdeletecategory', 'error', 'index.php', $categoryname);
+            throw new \moodle_exception('youcannotdeletecategory', 'error', 'index.php', $categoryname);
         }
 
         // Now build the form.
diff --git a/course/completion.php b/course/completion.php
index a5e7be30235b3..0a7f2d1f6e601 100644
--- a/course/completion.php
+++ b/course/completion.php
@@ -46,11 +46,11 @@
 
     if($id == SITEID){
         // Don't allow editing of 'site course' using this form.
-        print_error('cannoteditsiteform');
+        throw new \moodle_exception('cannoteditsiteform');
     }
 
     if (!$course = $DB->get_record('course', array('id'=>$id))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     require_login($course);
     $context = context_course::instance($course->id);
@@ -67,7 +67,7 @@
 
 } else {
     require_login();
-    print_error('needcourseid');
+    throw new \moodle_exception('needcourseid');
 }
 
 // Set up the page.
diff --git a/course/defaultcompletion.php b/course/defaultcompletion.php
index e9b03cca5b169..5e81eaf68869f 100644
--- a/course/defaultcompletion.php
+++ b/course/defaultcompletion.php
@@ -34,18 +34,18 @@
 
     if ($id == SITEID) {
         // Don't allow editing of 'site course' using this form.
-        print_error('cannoteditsiteform');
+        throw new \moodle_exception('cannoteditsiteform');
     }
 
     if (!$course = $DB->get_record('course', array('id' => $id))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     require_login($course);
     require_capability('moodle/course:manageactivities', context_course::instance($course->id));
 
 } else {
     require_login();
-    print_error('needcourseid');
+    throw new \moodle_exception('needcourseid');
 }
 
 // Set up the page.
diff --git a/course/delete.php b/course/delete.php
index 66bb257276f5c..c4a942ffe9c5d 100644
--- a/course/delete.php
+++ b/course/delete.php
@@ -36,7 +36,7 @@
 
 if ($SITE->id == $course->id || !can_delete_course($id)) {
     // Can not delete frontpage or don't have permission to delete the course.
-    print_error('cannotdeletecourse');
+    throw new \moodle_exception('cannotdeletecourse');
 }
 
 $categorycontext = context_coursecat::instance($course->category);
diff --git a/course/edit.php b/course/edit.php
index 616e62a708e39..93acabafc58d0 100644
--- a/course/edit.php
+++ b/course/edit.php
@@ -81,7 +81,7 @@
     // Editing course.
     if ($id == SITEID){
         // Don't allow editing of  'site course' using this from.
-        print_error('cannoteditsiteform');
+        throw new \moodle_exception('cannoteditsiteform');
     }
 
     // Login to the course and retrieve also all fields defined by course format.
diff --git a/course/editcategory.php b/course/editcategory.php
index f46448bd469a0..af6d13c8f0fbf 100644
--- a/course/editcategory.php
+++ b/course/editcategory.php
@@ -117,7 +117,7 @@
 } else if ($data = $mform->get_data()) {
     if (isset($coursecat)) {
         if ((int)$data->parent !== (int)$coursecat->parent && !$coursecat->can_change_parent($data->parent)) {
-            print_error('cannotmovecategory');
+            throw new \moodle_exception('cannotmovecategory');
         }
         $coursecat->update($data, $mform->get_description_editor_options());
     } else {
diff --git a/course/format/classes/output/local/content.php b/course/format/classes/output/local/content.php
index 79a52d2deb0e3..ea9da8a8376f7 100644
--- a/course/format/classes/output/local/content.php
+++ b/course/format/classes/output/local/content.php
@@ -140,7 +140,8 @@ protected function export_sections(\renderer_base $output): array {
             // The course/view.php check the section existence but the output can be called
             // from other parts so we need to check it.
             if (!$thissection) {
-                print_error('unknowncoursesection', 'error', course_get_url($course), format_string($course->fullname));
+                throw new \moodle_exception('unknowncoursesection', 'error', course_get_url($course),
+                    format_string($course->fullname));
             }
 
             $section = new $this->sectionclass($format, $thissection);
diff --git a/course/format/classes/output/section_renderer.php b/course/format/classes/output/section_renderer.php
index 545cf3b3271b9..db939119089e9 100644
--- a/course/format/classes/output/section_renderer.php
+++ b/course/format/classes/output/section_renderer.php
@@ -906,7 +906,7 @@ public function print_single_section_page($course, $sections, $mods, $modnames,
         if (!($sectioninfo = $modinfo->get_section_info($displaysection)) || !$sectioninfo->uservisible) {
             // This section doesn't exist or is not available for the user.
             // We actually already check this in course/view.php but just in case exit from this function as well.
-            print_error(
+            throw new \moodle_exception(
                 'unknowncoursesection',
                 'error',
                 course_get_url($course),
diff --git a/course/info.php b/course/info.php
index 6cb73c03ae126..e1f1f4d796fb7 100644
--- a/course/info.php
+++ b/course/info.php
@@ -28,16 +28,16 @@
     $name = optional_param('name', false, PARAM_RAW); // Course short name
 
     if (!$id and !$name) {
-        print_error("unspecifycourseid");
+        throw new \moodle_exception("unspecifycourseid");
     }
 
     if ($name) {
         if (!$course = $DB->get_record("course", array("shortname"=>$name))) {
-            print_error("invalidshortname");
+            throw new \moodle_exception("invalidshortname");
         }
     } else {
         if (!$course = $DB->get_record("course", array("id"=>$id))) {
-            print_error("invalidcourseid");
+            throw new \moodle_exception("invalidcourseid");
         }
     }
 
@@ -49,7 +49,7 @@
 
     $context = context_course::instance($course->id);
     if (!core_course_category::can_view_course_info($course) && !is_enrolled($context, null, '', true)) {
-        print_error('cannotviewcategory', '', $CFG->wwwroot .'/');
+        throw new \moodle_exception('cannotviewcategory', '', $CFG->wwwroot .'/');
     }
 
     $PAGE->set_course($course);
diff --git a/course/jumpto.php b/course/jumpto.php
index 98c4e49f79485..3cf232d5f1979 100644
--- a/course/jumpto.php
+++ b/course/jumpto.php
@@ -31,11 +31,11 @@
 $PAGE->set_url('/course/jumpto.php');
 
 if (!confirm_sesskey()) {
-    print_error('confirmsesskeybad');
+    throw new \moodle_exception('confirmsesskeybad');
 }
 
 if (strpos($jump, '/') === 0 || strpos($jump, $CFG->wwwroot) === 0) {
     redirect(new moodle_url($jump));
 } else {
-    print_error('error');
+    throw new \moodle_exception('error');
 }
diff --git a/course/lib.php b/course/lib.php
index 37c89ebc3e4cc..8fb28d6aa7d45 100644
--- a/course/lib.php
+++ b/course/lib.php
@@ -2694,7 +2694,7 @@ public function __construct($properties) {
         }
         if (empty($properties->requester)) {
             if (!($this->properties = $DB->get_record('course_request', array('id' => $properties->id)))) {
-                print_error('unknowncourserequest');
+                throw new \moodle_exception('unknowncourserequest');
             }
         } else {
             $this->properties = $properties;
diff --git a/course/loginas.php b/course/loginas.php
index d5db319229635..a85150d9dafd5 100644
--- a/course/loginas.php
+++ b/course/loginas.php
@@ -44,7 +44,7 @@
 
 if (has_capability('moodle/user:loginas', $systemcontext)) {
     if (is_siteadmin($userid)) {
-        print_error('nologinas');
+        throw new \moodle_exception('nologinas');
     }
     $context = $systemcontext;
     $PAGE->set_context($context);
@@ -52,10 +52,10 @@
     require_login($course);
     require_capability('moodle/user:loginas', $coursecontext);
     if (is_siteadmin($userid)) {
-        print_error('nologinas');
+        throw new \moodle_exception('nologinas');
     }
     if (!is_enrolled($coursecontext, $userid)) {
-        print_error('usernotincourse');
+        throw new \moodle_exception('usernotincourse');
     }
     $context = $coursecontext;
 
@@ -72,7 +72,7 @@
             }
         }
         if (!$samegroup) {
-            print_error('nologinas');
+            throw new \moodle_exception('nologinas');
         }
     }
 }
diff --git a/course/mod.php b/course/mod.php
index a6c33395a6b76..941684d0e0ef6 100644
--- a/course/mod.php
+++ b/course/mod.php
@@ -144,21 +144,21 @@
 
     if (!empty($movetosection)) {
         if (!$section = $DB->get_record('course_sections', array('id'=>$movetosection, 'course'=>$cm->course))) {
-            print_error('sectionnotexist');
+            throw new \moodle_exception('sectionnotexist');
         }
         $beforecm = NULL;
 
     } else {                      // normal moveto
         if (!$beforecm = get_coursemodule_from_id('', $moveto, $cm->course, true)) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
         if (!$section = $DB->get_record('course_sections', array('id'=>$beforecm->section, 'course'=>$cm->course))) {
-            print_error('sectionnotexist');
+            throw new \moodle_exception('sectionnotexist');
         }
     }
 
     if (!ismoving($section->course)) {
-        print_error('needcopy', '', "view.php?id=$section->course");
+        throw new \moodle_exception('needcopy', '', "view.php?id=$section->course");
     }
 
     moveto_module($cm, $section, $beforecm);
@@ -277,5 +277,5 @@
     unset($USER->activitycopysectionreturn);
     redirect(course_get_url($course, $cm->sectionnum, array('sr' => $sectionreturn)));
 } else {
-    print_error('unknowaction');
+    throw new \moodle_exception('unknowaction');
 }
diff --git a/course/modedit.php b/course/modedit.php
index 7a2088057da4f..4dace08a282a8 100644
--- a/course/modedit.php
+++ b/course/modedit.php
@@ -66,7 +66,7 @@
     $courseformat = course_get_format($course);
     $maxsections = $courseformat->get_max_sections();
     if ($section > $maxsections) {
-        print_error('maxsectionslimit', 'moodle', '', $maxsections);
+        throw new \moodle_exception('maxsectionslimit', 'moodle', '', $maxsections);
     }
 
     list($module, $context, $cw, $cm, $data) = prepare_new_moduleinfo_data($course, $add, $section);
@@ -127,7 +127,7 @@
 
 } else {
     require_login();
-    print_error('invalidaction');
+    throw new \moodle_exception('invalidaction');
 }
 
 $pagepath = 'mod-' . $module->name . '-';
@@ -145,7 +145,7 @@
 if (file_exists($modmoodleform)) {
     require_once($modmoodleform);
 } else {
-    print_error('noformdesc');
+    throw new \moodle_exception('noformdesc');
 }
 
 $mformclassname = 'mod_'.$module->name.'_mod_form';
@@ -169,7 +169,7 @@
     } else if (!empty($fromform->add)) {
         $fromform = add_moduleinfo($fromform, $course, $mform);
     } else {
-        print_error('invaliddata');
+        throw new \moodle_exception('invaliddata');
     }
 
     if (isset($fromform->submitbutton)) {
diff --git a/course/modlib.php b/course/modlib.php
index 2008c0a4be6ae..5ec9c375641d1 100644
--- a/course/modlib.php
+++ b/course/modlib.php
@@ -116,7 +116,7 @@ function add_moduleinfo($moduleinfo, $course, $mform = null) {
     $transaction = $DB->start_delegated_transaction();
 
     if (!$moduleinfo->coursemodule = add_course_module($newcm)) {
-        print_error('cannotaddcoursemodule');
+        throw new \moodle_exception('cannotaddcoursemodule');
     }
 
     if (plugin_supports('mod', $moduleinfo->modulename, FEATURE_MOD_INTRO, true) &&
@@ -142,9 +142,10 @@ function add_moduleinfo($moduleinfo, $course, $mform = null) {
         if ($returnfromfunc instanceof moodle_exception) {
             throw $returnfromfunc;
         } else if (!is_number($returnfromfunc)) {
-            print_error('invalidfunction', '', course_get_url($course, $moduleinfo->section));
+            throw new \moodle_exception('invalidfunction', '', course_get_url($course, $moduleinfo->section));
         } else {
-            print_error('cannotaddnewmodule', '', course_get_url($course, $moduleinfo->section), $moduleinfo->modulename);
+            throw new \moodle_exception('cannotaddnewmodule', '', course_get_url($course, $moduleinfo->section),
+                $moduleinfo->modulename);
         }
     }
 
@@ -493,7 +494,7 @@ function can_add_moduleinfo($course, $modulename, $section) {
     $cw = get_fast_modinfo($course)->get_section_info($section);
 
     if (!course_allowed_module($course, $module->name)) {
-        print_error('moduledisable');
+        throw new \moodle_exception('moduledisable');
     }
 
     return array($module, $context, $cw);
@@ -634,7 +635,7 @@ function update_moduleinfo($cm, $moduleinfo, $course, $mform = null) {
 
     $updateinstancefunction = $moduleinfo->modulename."_update_instance";
     if (!$updateinstancefunction($moduleinfo, $mform)) {
-        print_error('cannotupdatemod', '', course_get_url($course, $cm->section), $moduleinfo->modulename);
+        throw new \moodle_exception('cannotupdatemod', '', course_get_url($course, $cm->section), $moduleinfo->modulename);
     }
 
     // This needs to happen AFTER the grademin/grademax have already been updated.
@@ -655,7 +656,8 @@ function update_moduleinfo($cm, $moduleinfo, $course, $mform = null) {
                 $newgradeitem->grademax
             );
             if (!component_callback('mod_' . $moduleinfo->modulename, 'rescale_activity_grades', $params)) {
-                print_error('cannotreprocessgrades', '', course_get_url($course, $cm->section), $moduleinfo->modulename);
+                throw new \moodle_exception('cannotreprocessgrades', '', course_get_url($course, $cm->section),
+                    $moduleinfo->modulename);
             }
         }
     }
diff --git a/course/moodleform_mod.php b/course/moodleform_mod.php
index 0d47d96b604fe..ada5c5e81beec 100644
--- a/course/moodleform_mod.php
+++ b/course/moodleform_mod.php
@@ -123,7 +123,7 @@ public function __construct($current, $section, $cm, $course) {
             $matches = array();
             if (!preg_match('/^mod_([^_]+)_mod_form$/', get_class($this), $matches)) {
                 debugging('Rename form to mod_xx_mod_form, where xx is name of your module');
-                print_error('unknownmodulename');
+                throw new \moodle_exception('unknownmodulename');
             }
             $this->_modname = $matches[1];
         }
diff --git a/course/pending.php b/course/pending.php
index 8a0b88a37f881..c37b4e6fef087 100644
--- a/course/pending.php
+++ b/course/pending.php
@@ -67,7 +67,7 @@
             redirect(new moodle_url('/course/view.php', ['id' => $courseid]));
         }
     } else {
-        print_error('courseapprovedfailed');
+        throw new \moodle_exception('courseapprovedfailed');
     }
 }
 
diff --git a/course/recent.php b/course/recent.php
index a1bdca7e91de4..7dc2f2b70cf62 100644
--- a/course/recent.php
+++ b/course/recent.php
@@ -33,7 +33,7 @@
 $PAGE->set_pagelayout('report');
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error("That's an invalid course id");
+    throw new \moodle_exception("That's an invalid course id");
 }
 
 require_login($course);
@@ -67,7 +67,7 @@
 
 if (!empty($param->user)) {
     if (!$u = $DB->get_record('user', array('id'=>$param->user))) {
-        print_error("That's an invalid user!");
+        throw new \moodle_exception("That's an invalid user!");
     }
     $userinfo = fullname($u);
 }
diff --git a/course/request.php b/course/request.php
index 6e8d7cc7f6360..d27e860a5f8fd 100644
--- a/course/request.php
+++ b/course/request.php
@@ -43,10 +43,10 @@
 // Check permissions.
 require_login(null, false);
 if (isguestuser()) {
-    print_error('guestsarenotallowed', '', $returnurl);
+    throw new \moodle_exception('guestsarenotallowed', '', $returnurl);
 }
 if (empty($CFG->enablecourserequests)) {
-    print_error('courserequestdisabled', '', $returnurl);
+    throw new \moodle_exception('courserequestdisabled', '', $returnurl);
 }
 
 if ($CFG->lockrequestcategory) {
diff --git a/course/reset.php b/course/reset.php
index c8527c3f9c43c..412fe2b2f8839 100644
--- a/course/reset.php
+++ b/course/reset.php
@@ -33,7 +33,7 @@
 $id = required_param('id', PARAM_INT);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error("invalidcourseid");
+    throw new \moodle_exception("invalidcourseid");
 }
 
 $PAGE->set_url('/course/reset.php', array('id'=>$id));
diff --git a/course/tags.php b/course/tags.php
index 1c7ad66aedd22..8c78af7daf520 100644
--- a/course/tags.php
+++ b/course/tags.php
@@ -34,11 +34,11 @@
 // Check capabilities but do not call require_login($course) - the user does not have to be enrolled.
 $context = context_course::instance($course->id);
 if (!$course->visible and !has_capability('moodle/course:viewhiddencourses', $context)) {
-    print_error('coursehidden', '', $CFG->wwwroot .'/');
+    throw new \moodle_exception('coursehidden', '', $CFG->wwwroot .'/');
 }
 require_capability('moodle/course:tag', $context);
 if (!core_tag_tag::is_enabled('core', 'course')) {
-    print_error('tagsaredisabled', 'tag');
+    throw new \moodle_exception('tagsaredisabled', 'tag');
 }
 
 $PAGE->set_course($course);
diff --git a/course/togglecompletion.php b/course/togglecompletion.php
index ff02742f18748..c65a99b1c7c03 100644
--- a/course/togglecompletion.php
+++ b/course/togglecompletion.php
@@ -39,7 +39,7 @@
 $rolec = optional_param('rolec', 0, PARAM_INT);
 
 if (!$cmid && !$courseid) {
-    print_error('invalidarguments');
+    throw new \moodle_exception('invalidarguments');
 }
 
 // Process self completion
@@ -92,12 +92,12 @@
             $completion = $completion->get_completion($USER->id, COMPLETION_CRITERIA_TYPE_SELF);
 
             if (!$completion) {
-                print_error('noselfcompletioncriteria', 'completion');
+                throw new \moodle_exception('noselfcompletioncriteria', 'completion');
             }
 
             // Check if the user has already marked themselves as complete
             if ($completion->is_complete()) {
-                print_error('useralreadymarkedcomplete', 'completion');
+                throw new \moodle_exception('useralreadymarkedcomplete', 'completion');
             }
 
             $completion->mark_complete();
@@ -128,7 +128,7 @@
     case COMPLETION_INCOMPLETE:
         break;
     default:
-        print_error('unsupportedstate');
+        throw new \moodle_exception('unsupportedstate');
 }
 
 // Get course-modules entry
@@ -140,7 +140,7 @@
 require_capability('moodle/course:togglecompletion', context_module::instance($cmid));
 
 if (isguestuser() or !confirm_sesskey()) {
-    print_error('error');
+    throw new \moodle_exception('error');
 }
 
 // Set up completion object and check it is enabled.
diff --git a/course/view.php b/course/view.php
index 77ef8fae8978c..2f06e410ae673 100644
--- a/course/view.php
+++ b/course/view.php
@@ -27,7 +27,7 @@
     } else if (!empty($id)) {
         $params = array('id' => $id);
     }else {
-        print_error('unspecifycourseid', 'error');
+        throw new \moodle_exception('unspecifycourseid', 'error');
     }
 
     $course = $DB->get_record('course', $params, '*', MUST_EXIST);
diff --git a/customfield/classes/field_config_form.php b/customfield/classes/field_config_form.php
index 3d5d8bf73174d..53d1b5f54a1dd 100644
--- a/customfield/classes/field_config_form.php
+++ b/customfield/classes/field_config_form.php
@@ -158,7 +158,7 @@ protected function check_access_for_dynamic_submission(): void {
         $field = $this->get_field();
         $handler = $field->get_handler();
         if (!$handler->can_configure()) {
-            print_error('nopermissionconfigure', 'core_customfield');
+            throw new \moodle_exception('nopermissionconfigure', 'core_customfield');
         }
     }
 
diff --git a/draftfile.php b/draftfile.php
index 3c20e1241d239..61f549802bf4e 100644
--- a/draftfile.php
+++ b/draftfile.php
@@ -32,7 +32,7 @@
 
 require_login();
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 $relativepath = get_file_argument();
@@ -40,16 +40,16 @@
 
 // relative path must start with '/'
 if (!$relativepath) {
-    print_error('invalidargorconf');
+    throw new \moodle_exception('invalidargorconf');
 } else if ($relativepath[0] != '/') {
-    print_error('pathdoesnotstartslash');
+    throw new \moodle_exception('pathdoesnotstartslash');
 }
 
 // extract relative path components
 $args = explode('/', ltrim($relativepath, '/'));
 
 if (count($args) == 0) { // always at least user id
-    print_error('invalidarguments');
+    throw new \moodle_exception('invalidarguments');
 }
 
 $contextid = (int)array_shift($args);
@@ -68,7 +68,7 @@
 
 $userid = $context->instanceid;
 if ($USER->id != $userid) {
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 
diff --git a/enrol/index.php b/enrol/index.php
index 5a97c12ff51b3..75ccef7cd1cf8 100644
--- a/enrol/index.php
+++ b/enrol/index.php
@@ -49,7 +49,7 @@
 }
 
 if (!$course->visible && !has_capability('moodle/course:viewhiddencourses', context_course::instance($course->id))) {
-    print_error('coursehidden');
+    throw new \moodle_exception('coursehidden');
 }
 
 $PAGE->set_course($course);
@@ -58,12 +58,12 @@
 
 // do not allow enrols when in login-as session
 if (\core\session\manager::is_loggedinas() and $USER->loginascontext->contextlevel == CONTEXT_COURSE) {
-    print_error('loginasnoenrol', '', $CFG->wwwroot.'/course/view.php?id='.$USER->loginascontext->instanceid);
+    throw new \moodle_exception('loginasnoenrol', '', $CFG->wwwroot.'/course/view.php?id='.$USER->loginascontext->instanceid);
 }
 
 // Check if user has access to the category where the course is located.
 if (!core_course_category::can_view_course_info($course) && !is_enrolled($context, $USER, '', true)) {
-    print_error('coursehidden', '', $CFG->wwwroot . '/');
+    throw new \moodle_exception('coursehidden', '', $CFG->wwwroot . '/');
 }
 
 // get all enrol forms available in this course
diff --git a/enrol/lti/cartridge.php b/enrol/lti/cartridge.php
index 9428879ae891b..c3df932607be9 100644
--- a/enrol/lti/cartridge.php
+++ b/enrol/lti/cartridge.php
@@ -47,13 +47,13 @@
 $tool = \enrol_lti\helper::get_lti_tool($toolid);
 
 if (!is_enabled_auth('lti')) {
-    print_error('pluginnotenabled', 'auth', '', get_string('pluginname', 'auth_lti'));
+    throw new \moodle_exception('pluginnotenabled', 'auth', '', get_string('pluginname', 'auth_lti'));
 
 } else if (!enrol_is_enabled('lti')) {
-    print_error('enrolisdisabled', 'enrol_lti');
+    throw new \moodle_exception('enrolisdisabled', 'enrol_lti');
 
 } else if ($tool->status != ENROL_INSTANCE_ENABLED) {
-    print_error('enrolisdisabled', 'enrol_lti');
+    throw new \moodle_exception('enrolisdisabled', 'enrol_lti');
 
 } else {
     header('Content-Type: text/xml; charset=utf-8');
diff --git a/enrol/lti/classes/tool_provider.php b/enrol/lti/classes/tool_provider.php
index 0e181acd7ac05..6c54319ee774b 100644
--- a/enrol/lti/classes/tool_provider.php
+++ b/enrol/lti/classes/tool_provider.php
@@ -307,7 +307,7 @@ protected function onLaunch() {
                 $isforceembed = true;
             }
         } else {
-            print_error('invalidcontext');
+            throw new \moodle_exception('invalidcontext');
             exit();
         }
 
@@ -324,7 +324,7 @@ protected function onLaunch() {
 
         // Display an error, if there is one.
         if ($result !== helper::ENROLMENT_SUCCESSFUL) {
-            print_error($result, 'enrol_lti');
+            throw new \moodle_exception($result, 'enrol_lti');
             exit();
         }
 
diff --git a/enrol/lti/proxy.php b/enrol/lti/proxy.php
index 0819536a7f42c..557560d33d5c9 100644
--- a/enrol/lti/proxy.php
+++ b/enrol/lti/proxy.php
@@ -50,19 +50,19 @@
 $tool = \enrol_lti\helper::get_lti_tool($toolid);
 
 if (!is_enabled_auth('lti')) {
-    print_error('pluginnotenabled', 'auth', '', get_string('pluginname', 'auth_lti'));
+    throw new \moodle_exception('pluginnotenabled', 'auth', '', get_string('pluginname', 'auth_lti'));
     exit();
 }
 
 // Check if the enrolment plugin is disabled.
 if (!enrol_is_enabled('lti')) {
-    print_error('enrolisdisabled', 'enrol_lti');
+    throw new \moodle_exception('enrolisdisabled', 'enrol_lti');
     exit();
 }
 
 // Check if the enrolment instance is disabled.
 if ($tool->status != ENROL_INSTANCE_ENABLED) {
-    print_error('enrolisdisabled', 'enrol_lti');
+    throw new \moodle_exception('enrolisdisabled', 'enrol_lti');
     exit();
 }
 
@@ -70,7 +70,7 @@
 
 // Only accept proxy registration requests from this endpoint.
 if ($messagetype != "ToolProxyRegistrationRequest") {
-    print_error('invalidrequest', 'enrol_lti');
+    throw new \moodle_exception('invalidrequest', 'enrol_lti');
     exit();
 }
 
diff --git a/enrol/lti/tool.php b/enrol/lti/tool.php
index f3436cfaac4e2..6730d474f1c08 100644
--- a/enrol/lti/tool.php
+++ b/enrol/lti/tool.php
@@ -37,19 +37,19 @@
 
 // Check if the authentication plugin is disabled.
 if (!is_enabled_auth('lti')) {
-    print_error('pluginnotenabled', 'auth', '', get_string('pluginname', 'auth_lti'));
+    throw new \moodle_exception('pluginnotenabled', 'auth', '', get_string('pluginname', 'auth_lti'));
     exit();
 }
 
 // Check if the enrolment plugin is disabled.
 if (!enrol_is_enabled('lti')) {
-    print_error('enrolisdisabled', 'enrol_lti');
+    throw new \moodle_exception('enrolisdisabled', 'enrol_lti');
     exit();
 }
 
 // Check if the enrolment instance is disabled.
 if ($tool->status != ENROL_INSTANCE_ENABLED) {
-    print_error('enrolisdisabled', 'enrol_lti');
+    throw new \moodle_exception('enrolisdisabled', 'enrol_lti');
     exit();
 }
 
@@ -59,7 +59,7 @@
 
 // Only accept launch requests from this endpoint.
 if ($messagetype != "basic-lti-launch-request") {
-    print_error('invalidrequest', 'enrol_lti');
+    throw new \moodle_exception('invalidrequest', 'enrol_lti');
     exit();
 }
 
diff --git a/enrol/unenroluser.php b/enrol/unenroluser.php
index 4690c57516cc2..87f21e7908eb3 100644
--- a/enrol/unenroluser.php
+++ b/enrol/unenroluser.php
@@ -46,13 +46,13 @@
 require_login($course);
 
 if (!enrol_is_enabled($instance->enrol)) {
-    print_error('erroreditenrolment', 'enrol');
+    throw new \moodle_exception('erroreditenrolment', 'enrol');
 }
 
 $plugin = enrol_get_plugin($instance->enrol);
 
 if (!$plugin->allow_unenrol_user($instance, $ue) or !has_capability("enrol/$instance->enrol:unenrol", $context)) {
-    print_error('erroreditenrolment', 'enrol');
+    throw new \moodle_exception('erroreditenrolment', 'enrol');
 }
 
 $manager = new course_enrolment_manager($PAGE, $course, $filter);
diff --git a/file.php b/file.php
index ab0a80e04522d..10148fe580fba 100644
--- a/file.php
+++ b/file.php
@@ -41,16 +41,16 @@
 
 // relative path must start with '/', because of backup/restore!!!
 if (!$relativepath) {
-    print_error('invalidargorconf');
+    throw new \moodle_exception('invalidargorconf');
 } else if ($relativepath[0] != '/') {
-    print_error('pathdoesnotstartslash');
+    throw new \moodle_exception('pathdoesnotstartslash');
 }
 
 // extract relative path components
 $args = explode('/', ltrim($relativepath, '/'));
 
 if (count($args) == 0) { // always at least courseid, may search for index.html in course root
-    print_error('invalidarguments');
+    throw new \moodle_exception('invalidarguments');
 }
 
 $courseid = (int)array_shift($args);
diff --git a/filter/algebra/algebradebug.php b/filter/algebra/algebradebug.php
index cf5bf96d79f78..047bf873ce895 100644
--- a/filter/algebra/algebradebug.php
+++ b/filter/algebra/algebradebug.php
@@ -6,7 +6,7 @@
     require_once("../../config.php");
 
     if (!filter_is_enabled('algebra')) {
-        print_error('filternotenabled');
+        throw new \moodle_exception('filternotenabled');
     }
 
     require_once($CFG->libdir.'/filelib.php');
diff --git a/filter/algebra/pix.php b/filter/algebra/pix.php
index 8172b7822269f..e966363667360 100644
--- a/filter/algebra/pix.php
+++ b/filter/algebra/pix.php
@@ -10,7 +10,7 @@
     require_once('../../config.php');
 
     if (!filter_is_enabled('algebra')) {
-        print_error('filternotenabled');
+        throw new \moodle_exception('filternotenabled');
     }
 
     require_once($CFG->libdir.'/filelib.php');
@@ -27,7 +27,7 @@
         $image    = $args[0];
         $pathname = $CFG->dataroot.'/filter/algebra/'.$image;
     } else {
-        print_error('invalidarguments', 'error');
+        throw new \moodle_exception('invalidarguments', 'error');
     }
 
     if (!file_exists($pathname)) {
diff --git a/filter/manage.php b/filter/manage.php
index c3121291e0e8a..f10685fd3af47 100644
--- a/filter/manage.php
+++ b/filter/manage.php
@@ -49,7 +49,7 @@
 
 // This is a policy decision, rather than something that would be impossible to implement.
 if (!in_array($context->contextlevel, array(CONTEXT_COURSECAT, CONTEXT_COURSE, CONTEXT_MODULE))) {
-    print_error('cannotcustomisefiltersblockuser', 'error');
+    throw new \moodle_exception('cannotcustomisefiltersblockuser', 'error');
 }
 
 $isfrontpage = ($context->contextlevel == CONTEXT_COURSE && $context->instanceid == SITEID);
@@ -74,13 +74,13 @@
 /// Get the list of available filters.
 $availablefilters = filter_get_available_in_context($context);
 if (!$isfrontpage && empty($availablefilters)) {
-    print_error('nofiltersenabled', 'error');
+    throw new \moodle_exception('nofiltersenabled', 'error');
 }
 
 // If we are handling local settings for a particular filter, start processing.
 if ($forfilter) {
     if (!filter_has_local_settings($forfilter)) {
-        print_error('filterdoesnothavelocalconfig', 'error', $forfilter);
+        throw new \moodle_exception('filterdoesnothavelocalconfig', 'error', $forfilter);
     }
     require_once($CFG->dirroot . '/filter/local_settings_form.php');
     require_once($CFG->dirroot . '/filter/' . $forfilter . '/filterlocalsettings.php');
diff --git a/filter/mediaplugin/dev/perftest.php b/filter/mediaplugin/dev/perftest.php
index 2ad68a6d4cd72..7bfb03a14ace7 100644
--- a/filter/mediaplugin/dev/perftest.php
+++ b/filter/mediaplugin/dev/perftest.php
@@ -31,7 +31,7 @@
 // Only available to site admins.
 require_login();
 if (!is_siteadmin()) {
-    print_error('nopermissions', 'error', '', 'perftest');
+    throw new \moodle_exception('nopermissions', 'error', '', 'perftest');
 }
 
 // Set up page.
diff --git a/filter/tex/displaytex.php b/filter/tex/displaytex.php
index 76eb64aec45a7..07b9a7cab7e2d 100644
--- a/filter/tex/displaytex.php
+++ b/filter/tex/displaytex.php
@@ -30,7 +30,7 @@
 require('../../config.php');
 
 if (!filter_is_enabled('tex') and !filter_is_enabled('algebra')) {
-    print_error('filternotenabled');
+    throw new \moodle_exception('filternotenabled');
 }
 
 $texexp = optional_param('texexp', '', PARAM_RAW);
diff --git a/filter/tex/lib.php b/filter/tex/lib.php
index 9a0fe3c9c5891..a4f8bba078cba 100644
--- a/filter/tex/lib.php
+++ b/filter/tex/lib.php
@@ -37,7 +37,7 @@ function filter_tex_get_executable($debug=false) {
         if (is_executable($pathmimetex)) {
             return $pathmimetex;
         } else {
-            print_error('mimetexnotexecutable', 'error');
+            throw new \moodle_exception('mimetexnotexecutable', 'error');
         }
     }
 
@@ -46,7 +46,7 @@ function filter_tex_get_executable($debug=false) {
         if (is_executable($custom_commandpath)) {
             return $custom_commandpath;
         } else {
-            print_error('mimetexnotexecutable', 'error');
+            throw new \moodle_exception('mimetexnotexecutable', 'error');
         }
     }
 
@@ -61,7 +61,7 @@ function filter_tex_get_executable($debug=false) {
             return "$CFG->dirroot/filter/tex/mimetex.linux";
     }
 
-    print_error('mimetexisnotexist', 'error');
+    throw new \moodle_exception('mimetexisnotexist', 'error');
 }
 
 /**
diff --git a/filter/tex/pix.php b/filter/tex/pix.php
index d66faf223948e..570e47330faeb 100644
--- a/filter/tex/pix.php
+++ b/filter/tex/pix.php
@@ -10,7 +10,7 @@
     require_once('../../config.php');
 
     if (!filter_is_enabled('tex')) {
-        print_error('filternotenabled');
+        throw new \moodle_exception('filternotenabled');
     }
 
     require_once($CFG->libdir.'/filelib.php');
@@ -28,7 +28,7 @@
         $image    = $args[0];
         $pathname = $CFG->dataroot.'/filter/tex/'.$image;
     } else {
-        print_error('invalidarguments', 'error');
+        throw new \moodle_exception('invalidarguments', 'error');
     }
 
     if (!file_exists($pathname)) {
diff --git a/filter/tex/texdebug.php b/filter/tex/texdebug.php
index 36808f1b928b6..5de6ccbd05598 100644
--- a/filter/tex/texdebug.php
+++ b/filter/tex/texdebug.php
@@ -29,7 +29,7 @@
     require_once("../../config.php");
 
     if (!filter_is_enabled('tex')) {
-        print_error('filternotenabled');
+        throw new \moodle_exception('filternotenabled');
     }
 
     require_once($CFG->libdir.'/filelib.php');
diff --git a/grade/edit/letter/index.php b/grade/edit/letter/index.php
index 24f9769c16f3c..bffdb11ff6776 100644
--- a/grade/edit/letter/index.php
+++ b/grade/edit/letter/index.php
@@ -38,7 +38,7 @@
 //if viewing
 if (!$edit) {
     if (!has_capability('moodle/grade:manage', $context) and !has_capability('moodle/grade:manageletters', $context)) {
-        print_error('nopermissiontoviewletergrade');
+        throw new \moodle_exception('nopermissiontoviewletergrade');
     }
 } else {//else we're editing
     require_capability('moodle/grade:manageletters', $context);
@@ -71,7 +71,7 @@
 
     $gpr = new grade_plugin_return(array('type'=>'edit', 'plugin'=>'letter', 'courseid'=>$course->id));
 } else {
-    print_error('invalidcourselevel');
+    throw new \moodle_exception('invalidcourselevel');
 }
 
 $strgrades = get_string('grades');
diff --git a/grade/edit/outcome/edit.php b/grade/edit/outcome/edit.php
index a5b58f528c8d1..acb823539b73f 100644
--- a/grade/edit/outcome/edit.php
+++ b/grade/edit/outcome/edit.php
@@ -49,12 +49,12 @@
 
     /// editing existing outcome
     if (!$outcome_rec = $DB->get_record('grade_outcomes', array('id' => $id))) {
-        print_error('invalidoutcome');
+        throw new \moodle_exception('invalidoutcome');
     }
     if ($outcome_rec->courseid) {
         $outcome_rec->standard = 0;
         if (!$course = $DB->get_record('course', array('id' => $outcome_rec->courseid))) {
-            print_error('invalidcourseid');
+            throw new \moodle_exception('invalidcourseid');
         }
         require_login($course);
         $context = context_course::instance($course->id);
@@ -63,7 +63,7 @@
     } else {
         if ($courseid) {
             if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-                print_error('invalidcourseid');
+                throw new \moodle_exception('invalidcourseid');
             }
         }
         $outcome_rec->standard = 1;
diff --git a/grade/edit/outcome/export.php b/grade/edit/outcome/export.php
index 65179a7a76f7d..ec530ea031f0f 100644
--- a/grade/edit/outcome/export.php
+++ b/grade/edit/outcome/export.php
@@ -32,7 +32,7 @@
 /// Make sure they can even access this course
 if ($courseid) {
     if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     require_login($course);
     $context = context_course::instance($course->id);
diff --git a/grade/edit/outcome/import.php b/grade/edit/outcome/import.php
index 6a6b0d02df399..e3a5cc82d3218 100644
--- a/grade/edit/outcome/import.php
+++ b/grade/edit/outcome/import.php
@@ -39,7 +39,7 @@
 /// Make sure they can even access this course
 if ($courseid) {
     if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     require_login($course);
     $context = context_course::instance($course->id);
diff --git a/grade/edit/outcome/index.php b/grade/edit/outcome/index.php
index 84312e6037b17..7b3a607315fbd 100644
--- a/grade/edit/outcome/index.php
+++ b/grade/edit/outcome/index.php
@@ -82,7 +82,7 @@
         if (empty($outcome->courseid)) {
             require_capability('moodle/grade:manage', context_system::instance());
         } else if ($outcome->courseid != $courseid) {
-            print_error('invalidcourseid');
+            throw new \moodle_exception('invalidcourseid');
         }
 
         if (!$outcome->can_delete()) {
diff --git a/grade/edit/scale/edit.php b/grade/edit/scale/edit.php
index a8f3c172c9ce8..93f0e3c5d17c7 100644
--- a/grade/edit/scale/edit.php
+++ b/grade/edit/scale/edit.php
@@ -41,12 +41,12 @@
 if ($id) {
     /// editing existing scale
     if (!$scale_rec = $DB->get_record('scale', array('id' => $id))) {
-        print_error('invalidscaleid');
+        throw new \moodle_exception('invalidscaleid');
     }
     if ($scale_rec->courseid) {
         $scale_rec->standard = 0;
         if (!$course = $DB->get_record('course', array('id' => $scale_rec->courseid))) {
-            print_error('invalidcourseid');
+            throw new \moodle_exception('invalidcourseid');
         }
         require_login($course);
         $context = context_course::instance($course->id);
@@ -55,7 +55,7 @@
     } else {
         if ($courseid) {
             if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-                print_error('invalidcourseid');
+                throw new \moodle_exception('invalidcourseid');
             }
         }
         $scale_rec->standard = 1;
@@ -67,7 +67,7 @@
 } else if ($courseid){
     /// adding new scale from course
     if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     $scale_rec = new stdClass();
     $scale_rec->standard = 0;
diff --git a/grade/edit/scale/index.php b/grade/edit/scale/index.php
index 7fcf1d778fb79..f9e6e18f6377f 100644
--- a/grade/edit/scale/index.php
+++ b/grade/edit/scale/index.php
@@ -34,7 +34,7 @@
 /// Make sure they can even access this course
 if ($courseid) {
     if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     require_login($course);
     $context = context_course::instance($course->id);
@@ -72,7 +72,7 @@
         if (empty($scale->courseid)) {
             require_capability('moodle/course:managescales', context_system::instance());
         } else if ($scale->courseid != $courseid) {
-            print_error('invalidcourseid');
+            throw new \moodle_exception('invalidcourseid');
         }
 
         if (!$scale->can_delete()) {
diff --git a/grade/edit/settings/index.php b/grade/edit/settings/index.php
index f9b756b28b1d4..eac3a216d622c 100644
--- a/grade/edit/settings/index.php
+++ b/grade/edit/settings/index.php
@@ -33,7 +33,7 @@
 $PAGE->set_pagelayout('admin');
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login($course);
 $context = context_course::instance($course->id);
diff --git a/grade/edit/tree/action.php b/grade/edit/tree/action.php
index 1117f9d3c6374..3602883916a03 100644
--- a/grade/edit/tree/action.php
+++ b/grade/edit/tree/action.php
@@ -33,7 +33,7 @@
 
 /// Make sure they can even access this course
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login($course);
 $context = context_course::instance($course->id);
@@ -47,7 +47,7 @@
 
 // what are we working with?
 if (!$element = $gtree->locate_element($eid)) {
-    print_error('invalidelementid', '', $returnurl);
+    throw new \moodle_exception('invalidelementid', '', $returnurl);
 }
 $object = $element['object'];
 $type   = $element['type'];
@@ -57,13 +57,13 @@
     case 'hide':
         if ($eid and confirm_sesskey()) {
             if (!has_capability('moodle/grade:manage', $context) and !has_capability('moodle/grade:hide', $context)) {
-                print_error('nopermissiontohide', '', $returnurl);
+                throw new \moodle_exception('nopermissiontohide', '', $returnurl);
             }
             if ($type == 'grade' and empty($object->id)) {
                 $object->insert();
             }
             if (!$object->can_control_visibility()) {
-                print_error('componentcontrolsvisibility', 'grades', $returnurl);
+                throw new \moodle_exception('componentcontrolsvisibility', 'grades', $returnurl);
             }
             $object->set_hidden(1, true);
         }
@@ -72,13 +72,13 @@
     case 'show':
         if ($eid and confirm_sesskey()) {
             if (!has_capability('moodle/grade:manage', $context) and !has_capability('moodle/grade:hide', $context)) {
-                print_error('nopermissiontoshow', '', $returnurl);
+                throw new \moodle_exception('nopermissiontoshow', '', $returnurl);
             }
             if ($type == 'grade' and empty($object->id)) {
                 $object->insert();
             }
             if (!$object->can_control_visibility()) {
-                print_error('componentcontrolsvisibility', 'grades', $returnurl);
+                throw new \moodle_exception('componentcontrolsvisibility', 'grades', $returnurl);
             }
             $object->set_hidden(0, true);
         }
@@ -87,7 +87,7 @@
     case 'lock':
         if ($eid and confirm_sesskey()) {
             if (!has_capability('moodle/grade:manage', $context) and !has_capability('moodle/grade:lock', $context)) {
-                print_error('nopermissiontolock', '', $returnurl);
+                throw new \moodle_exception('nopermissiontolock', '', $returnurl);
             }
             if ($type == 'grade' and empty($object->id)) {
                 $object->insert();
@@ -99,7 +99,7 @@
     case 'unlock':
         if ($eid and confirm_sesskey()) {
             if (!has_capability('moodle/grade:manage', $context) and !has_capability('moodle/grade:unlock', $context)) {
-                print_error('nopermissiontounlock', '', $returnurl);
+                throw new \moodle_exception('nopermissiontounlock', '', $returnurl);
             }
             if ($type == 'grade' and empty($object->id)) {
                 $object->insert();
@@ -115,7 +115,7 @@
             // only be done by someone who can manage the grades.
             if ($type != 'category' || $object->aggregation != GRADE_AGGREGATE_SUM ||
                     !has_capability('moodle/grade:manage', $context)) {
-                print_error('nopermissiontoresetweights', 'grades', $returnurl);
+                throw new \moodle_exception('nopermissiontoresetweights', 'grades', $returnurl);
             }
 
             // Remove the weightoverride flag from the children.
diff --git a/grade/edit/tree/calculation.php b/grade/edit/tree/calculation.php
index 1e984beed3f84..360b2a267d8be 100644
--- a/grade/edit/tree/calculation.php
+++ b/grade/edit/tree/calculation.php
@@ -39,7 +39,7 @@
 $PAGE->set_url($url);
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -55,7 +55,7 @@
 $returnurl = $gpr->get_return_url($CFG->wwwroot.'/grade/report/index.php?id='.$course->id);
 
 if (!$grade_item = grade_item::fetch(array('id'=>$id, 'courseid'=>$course->id))) {
-    print_error('invaliditemid');
+    throw new \moodle_exception('invaliditemid');
 }
 
 // activity items and items without grade can not have calculation
diff --git a/grade/edit/tree/category.php b/grade/edit/tree/category.php
index f9f1453c1af8f..3daddf7c1de07 100644
--- a/grade/edit/tree/category.php
+++ b/grade/edit/tree/category.php
@@ -41,7 +41,7 @@
     array('id'=>$courseid)));
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -57,7 +57,7 @@
 
 if ($id) {
     if (!$grade_category = grade_category::fetch(array('id'=>$id, 'courseid'=>$course->id))) {
-        print_error('invalidcategory');
+        throw new \moodle_exception('invalidcategory');
     }
     $grade_category->apply_forced_settings();
     $category = $grade_category->get_record_data();
diff --git a/grade/edit/tree/grade.php b/grade/edit/tree/grade.php
index 698cde7b8cc63..a710b24cc55c0 100644
--- a/grade/edit/tree/grade.php
+++ b/grade/edit/tree/grade.php
@@ -45,7 +45,7 @@
 $PAGE->set_url($url);
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 $PAGE->set_pagelayout('incourse');
@@ -62,27 +62,27 @@
 // security checks!
 if (!empty($id)) {
     if (!$grade = $DB->get_record('grade_grades', array('id' => $id))) {
-        print_error('invalidgroupid');
+        throw new \moodle_exception('invalidgroupid');
     }
 
     if (!empty($itemid) and $itemid != $grade->itemid) {
-        print_error('invaliditemid');
+        throw new \moodle_exception('invaliditemid');
     }
     $itemid = $grade->itemid;
 
     if (!empty($userid) and $userid != $grade->userid) {
-        print_error('invaliduser');
+        throw new \moodle_exception('invaliduser');
     }
     $userid = $grade->userid;
 
     unset($grade);
 
 } else if (empty($userid) or empty($itemid)) {
-    print_error('missinguseranditemid');
+    throw new \moodle_exception('missinguseranditemid');
 }
 
 if (!$grade_item = grade_item::fetch(array('id'=>$itemid, 'courseid'=>$courseid))) {
-    print_error('cannotfindgradeitem');
+    throw new \moodle_exception('cannotfindgradeitem');
 }
 
 // now verify grading user has access to all groups or is member of the same group when separate groups used in course
@@ -95,10 +95,10 @@
             }
         }
         if (!$ok) {
-            print_error('cannotgradeuser');
+            throw new \moodle_exception('cannotgradeuser');
         }
     } else {
-        print_error('cannotgradeuser');
+        throw new \moodle_exception('cannotgradeuser');
     }
 }
 
diff --git a/grade/edit/tree/index.php b/grade/edit/tree/index.php
index b83efdbf8238b..c84b9700ec83f 100644
--- a/grade/edit/tree/index.php
+++ b/grade/edit/tree/index.php
@@ -40,7 +40,7 @@
 
 /// Make sure they can even access this course
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -63,7 +63,7 @@
 
 } else {
     if (!$element = $gtree->locate_element($eid)) {
-        print_error('invalidelementid', '', $returnurl);
+        throw new \moodle_exception('invalidelementid', '', $returnurl);
     }
     $object = $element['object'];
 }
@@ -89,7 +89,7 @@
     case 'duplicate':
         if ($eid and confirm_sesskey()) {
             if (!$el = $gtree->locate_element($eid)) {
-                print_error('invalidelementid', '', $returnurl);
+                throw new \moodle_exception('invalidelementid', '', $returnurl);
             }
 
             $object->duplicate();
@@ -136,7 +136,7 @@
             $first = optional_param('first', false,  PARAM_BOOL); // If First is set to 1, it means the target is the first child of the category $moveafter
 
             if(!$after_el = $gtree->locate_element($moveafter)) {
-                print_error('invalidelementid', '', $returnurl);
+                throw new \moodle_exception('invalidelementid', '', $returnurl);
             }
 
             $after = $after_el['object'];
diff --git a/grade/edit/tree/item.php b/grade/edit/tree/item.php
index 3f6ec64ffc536..5f96e8cbd6dcc 100644
--- a/grade/edit/tree/item.php
+++ b/grade/edit/tree/item.php
@@ -41,7 +41,7 @@
     array('id'=>$courseid)));
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/edit/tree/lib.php b/grade/edit/tree/lib.php
index e4435bce6b9f8..7dabc375161b1 100644
--- a/grade/edit/tree/lib.php
+++ b/grade/edit/tree/lib.php
@@ -503,7 +503,7 @@ function move_elements($eids, $returnurl) {
         }
 
         if(!$after_el = $this->gtree->locate_element("cg$moveafter")) {
-            print_error('invalidelementid', '', $returnurl);
+            throw new \moodle_exception('invalidelementid', '', $returnurl);
         }
 
         $after = $after_el['object'];
@@ -512,7 +512,7 @@ function move_elements($eids, $returnurl) {
 
         foreach ($eids as $eid) {
             if (!$element = $this->gtree->locate_element($eid)) {
-                print_error('invalidelementid', '', $returnurl);
+                throw new \moodle_exception('invalidelementid', '', $returnurl);
             }
             $object = $element['object'];
 
@@ -1046,7 +1046,7 @@ public function get_category_cell($category, $levelclass, $params) {
 
     public function get_item_cell($item, $params) {
         if (empty($params['itemtype']) || empty($params['eid'])) {
-            print_error('missingitemtypeoreid', 'core_grades');
+            throw new \moodle_exception('missingitemtypeoreid', 'core_grades');
         }
         $itemcell = parent::get_item_cell($item, $params);
 
diff --git a/grade/edit/tree/outcomeitem.php b/grade/edit/tree/outcomeitem.php
index 5d0a628adad4b..ed5dbed2d6947 100644
--- a/grade/edit/tree/outcomeitem.php
+++ b/grade/edit/tree/outcomeitem.php
@@ -40,7 +40,7 @@
     array('id'=>$courseid)));
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/export/key.php b/grade/export/key.php
index 2bee1a16094a7..ba3b2b6d3bb6f 100644
--- a/grade/export/key.php
+++ b/grade/export/key.php
@@ -37,22 +37,22 @@
 
 if ($id) {
     if (!$key = $DB->get_record('user_private_key', array('id' => $id))) {
-        print_error('invalidgroupid');
+        throw new \moodle_exception('invalidgroupid');
     }
     if (empty($courseid)) {
         $courseid = $key->instance;
 
     } else if ($courseid != $key->instance) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
     if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
 } else {
     if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     $key = new stdClass();
 }
@@ -66,12 +66,12 @@
 // Check if the user has at least one grade publishing capability.
 $plugins = grade_helper::get_plugins_export($course->id);
 if (!isset($plugins['keymanager'])) {
-    print_error('nopermissions');
+    throw new \moodle_exception('nopermissions');
 }
 
 // extra security check
 if (!empty($key->userid) and $USER->id != $key->userid) {
-    print_error('notownerofkey');
+    throw new \moodle_exception('notownerofkey');
 }
 
 $returnurl = $CFG->wwwroot.'/grade/export/keymanager.php?id='.$course->id;
diff --git a/grade/export/keymanager.php b/grade/export/keymanager.php
index 9ce3631ce4cfe..ad9ddd506d388 100644
--- a/grade/export/keymanager.php
+++ b/grade/export/keymanager.php
@@ -31,7 +31,7 @@
 $PAGE->set_url('/grade/export/keymanager.php', array('id' => $id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -42,7 +42,7 @@
 // Check if the user has at least one grade publishing capability.
 $plugins = grade_helper::get_plugins_export($course->id);
 if (!isset($plugins['keymanager'])) {
-    print_error('nopermissions');
+    throw new \moodle_exception('nopermissions');
 }
 
 $actionbar = new \core_grades\output\export_key_manager_action_bar($context);
diff --git a/grade/export/ods/dump.php b/grade/export/ods/dump.php
index 80b2c5a3c295d..8b2c5a6fee1f0 100644
--- a/grade/export/ods/dump.php
+++ b/grade/export/ods/dump.php
@@ -28,13 +28,13 @@
 $onlyactive         = optional_param('export_onlyactive', 0, PARAM_BOOL);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_user_key_login('grade/export', $id); // we want different keys for each course
 
 if (empty($CFG->gradepublishing)) {
-    print_error('gradepubdisable');
+    throw new \moodle_exception('gradepubdisable');
 }
 
 $context = context_course::instance($id);
@@ -43,7 +43,7 @@
 require_capability('gradeexport/ods:publish', $context);
 
 if (!groups_group_visible($groupid, $COURSE)) {
-    print_error('cannotaccessgroup', 'grades');
+    throw new \moodle_exception('cannotaccessgroup', 'grades');
 }
 
 // Get all url parameters and create an object to simulate a form submission.
diff --git a/grade/export/ods/export.php b/grade/export/ods/export.php
index 4d695ad11ef32..9f0984a5ce995 100644
--- a/grade/export/ods/export.php
+++ b/grade/export/ods/export.php
@@ -23,7 +23,7 @@
 $PAGE->set_url('/grade/export/ods/export.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -45,7 +45,7 @@
 
 if (groups_get_course_groupmode($COURSE) == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $context)) {
     if (!groups_is_member($groupid, $USER->id)) {
-        print_error('cannotaccessgroup', 'grades');
+        throw new \moodle_exception('cannotaccessgroup', 'grades');
     }
 }
 $mform = new grade_export_form(null, array('publishing' => true, 'simpleui' => true, 'multipledisplaytypes' => true));
diff --git a/grade/export/ods/index.php b/grade/export/ods/index.php
index a1fb7b70de431..69dc1c6bb357d 100644
--- a/grade/export/ods/index.php
+++ b/grade/export/ods/index.php
@@ -24,7 +24,7 @@
 $PAGE->set_url('/grade/export/ods/index.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/export/txt/dump.php b/grade/export/txt/dump.php
index 79f1d432b8a2b..27a1abbd63818 100644
--- a/grade/export/txt/dump.php
+++ b/grade/export/txt/dump.php
@@ -29,13 +29,13 @@
 $onlyactive         = optional_param('export_onlyactive', 0, PARAM_BOOL);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_user_key_login('grade/export', $id); // we want different keys for each course
 
 if (empty($CFG->gradepublishing)) {
-    print_error('gradepubdisable');
+    throw new \moodle_exception('gradepubdisable');
 }
 
 $context = context_course::instance($id);
@@ -44,7 +44,7 @@
 require_capability('gradeexport/txt:view', $context);
 
 if (!groups_group_visible($groupid, $COURSE)) {
-    print_error('cannotaccessgroup', 'grades');
+    throw new \moodle_exception('cannotaccessgroup', 'grades');
 }
 
 // Get all url parameters and create an object to simulate a form submission.
diff --git a/grade/export/txt/export.php b/grade/export/txt/export.php
index 2de9ba8482a3a..29dce0ac560ab 100644
--- a/grade/export/txt/export.php
+++ b/grade/export/txt/export.php
@@ -23,7 +23,7 @@
 $PAGE->set_url('/grade/export/txt/export.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -45,7 +45,7 @@
 
 if (groups_get_course_groupmode($COURSE) == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $context)) {
     if (!groups_is_member($groupid, $USER->id)) {
-        print_error('cannotaccessgroup', 'grades');
+        throw new \moodle_exception('cannotaccessgroup', 'grades');
     }
 }
 
diff --git a/grade/export/txt/index.php b/grade/export/txt/index.php
index 24c70bab0a6b7..c21eee122549b 100644
--- a/grade/export/txt/index.php
+++ b/grade/export/txt/index.php
@@ -24,7 +24,7 @@
 $PAGE->set_url('/grade/export/txt/index.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/export/xls/dump.php b/grade/export/xls/dump.php
index 5459c043b1d83..84ba6384a1fd4 100644
--- a/grade/export/xls/dump.php
+++ b/grade/export/xls/dump.php
@@ -28,13 +28,13 @@
 $onlyactive         = optional_param('export_onlyactive', 0, PARAM_BOOL);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_user_key_login('grade/export', $id); // we want different keys for each course
 
 if (empty($CFG->gradepublishing)) {
-    print_error('gradepubdisable');
+    throw new \moodle_exception('gradepubdisable');
 }
 
 $context = context_course::instance($id);
@@ -43,7 +43,7 @@
 require_capability('gradeexport/xls:publish', $context);
 
 if (!groups_group_visible($groupid, $COURSE)) {
-    print_error('cannotaccessgroup', 'grades');
+    throw new \moodle_exception('cannotaccessgroup', 'grades');
 }
 
 // Get all url parameters and create an object to simulate a form submission.
diff --git a/grade/export/xls/export.php b/grade/export/xls/export.php
index 3a1603d94c78d..9410a0101477d 100644
--- a/grade/export/xls/export.php
+++ b/grade/export/xls/export.php
@@ -23,7 +23,7 @@
 $PAGE->set_url('/grade/export/xls/export.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -45,7 +45,7 @@
 
 if (groups_get_course_groupmode($COURSE) == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $context)) {
     if (!groups_is_member($groupid, $USER->id)) {
-        print_error('cannotaccessgroup', 'grades');
+        throw new \moodle_exception('cannotaccessgroup', 'grades');
     }
 }
 $mform = new grade_export_form(null, array('publishing' => true, 'simpleui' => true, 'multipledisplaytypes' => true));
diff --git a/grade/export/xls/index.php b/grade/export/xls/index.php
index 4654d9300993a..207a0a9bacb0e 100644
--- a/grade/export/xls/index.php
+++ b/grade/export/xls/index.php
@@ -24,7 +24,7 @@
 $PAGE->set_url('/grade/export/xls/index.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/export/xml/dump.php b/grade/export/xml/dump.php
index 592b1f417b138..ebaf138d34480 100644
--- a/grade/export/xml/dump.php
+++ b/grade/export/xml/dump.php
@@ -29,13 +29,13 @@
 $onlyactive         = optional_param('export_onlyactive', 0, PARAM_BOOL);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_user_key_login('grade/export', $id); // we want different keys for each course
 
 if (empty($CFG->gradepublishing)) {
-    print_error('gradepubdisable');
+    throw new \moodle_exception('gradepubdisable');
 }
 
 $context = context_course::instance($id);
@@ -44,7 +44,7 @@
 require_capability('gradeexport/xml:view', $context);
 
 if (!groups_group_visible($groupid, $COURSE)) {
-    print_error('cannotaccessgroup', 'grades');
+    throw new \moodle_exception('cannotaccessgroup', 'grades');
 }
 
 // Get all url parameters and create an object to simulate a form submission.
diff --git a/grade/export/xml/export.php b/grade/export/xml/export.php
index ba0d448326faf..abe99807ec819 100644
--- a/grade/export/xml/export.php
+++ b/grade/export/xml/export.php
@@ -23,7 +23,7 @@
 $PAGE->set_url('/grade/export/xml/export.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -45,7 +45,7 @@
 
 if (groups_get_course_groupmode($COURSE) == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $context)) {
     if (!groups_is_member($groupid, $USER->id)) {
-        print_error('cannotaccessgroup', 'grades');
+        throw new \moodle_exception('cannotaccessgroup', 'grades');
     }
 }
 $mform = new grade_export_form(null, array('publishing' => true, 'simpleui' => true, 'multipledisplaytypes' => false,
diff --git a/grade/export/xml/grade_export_xml.php b/grade/export/xml/grade_export_xml.php
index 865da1a979e7b..012b152a0a7b5 100644
--- a/grade/export/xml/grade_export_xml.php
+++ b/grade/export/xml/grade_export_xml.php
@@ -68,7 +68,7 @@ public function print_grades($feedback = false) {
         make_temp_directory('gradeexport');
         $tempfilename = $CFG->tempdir .'/gradeexport/'. md5(sesskey().microtime().$downloadfilename);
         if (!$handle = fopen($tempfilename, 'w+b')) {
-            print_error('cannotcreatetempdir');
+            throw new \moodle_exception('cannotcreatetempdir');
         }
 
         /// time stamp to ensure uniqueness of batch export
diff --git a/grade/export/xml/index.php b/grade/export/xml/index.php
index 530a4a4fde77a..8091807ff21bd 100644
--- a/grade/export/xml/index.php
+++ b/grade/export/xml/index.php
@@ -24,7 +24,7 @@
 $PAGE->set_url('/grade/export/xml/index.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/import/csv/classes/load_data.php b/grade/import/csv/classes/load_data.php
index 2167eb2d497a6..28d13f918b4c7 100644
--- a/grade/import/csv/classes/load_data.php
+++ b/grade/import/csv/classes/load_data.php
@@ -480,7 +480,7 @@ public function prepare_import_grade_data($header, $formdata, $csvimport, $cours
                     $maperrors[$j] = true;
                 } else {
                     // Collision.
-                    print_error('cannotmapfield', '', '', $j);
+                    throw new \moodle_exception('cannotmapfield', '', '', $j);
                 }
             }
         }
diff --git a/grade/import/csv/index.php b/grade/import/csv/index.php
index b72d3775b42f6..7b8513ec5a815 100644
--- a/grade/import/csv/index.php
+++ b/grade/import/csv/index.php
@@ -39,7 +39,7 @@
 $PAGE->set_url($url);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/import/direct/index.php b/grade/import/direct/index.php
index e5ea3373a4ee6..1d61a18b73622 100644
--- a/grade/import/direct/index.php
+++ b/grade/import/direct/index.php
@@ -35,7 +35,7 @@
 $PAGE->set_url($url);
 
 if (!$course = $DB->get_record('course', array('id' => $id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/import/key.php b/grade/import/key.php
index 44245008e9c9b..34d7eb7f2c0a3 100644
--- a/grade/import/key.php
+++ b/grade/import/key.php
@@ -38,22 +38,22 @@
 
 if ($id) {
     if (!$key = $DB->get_record('user_private_key', array('id' => $id))) {
-        print_error('invalidgroupid');
+        throw new \moodle_exception('invalidgroupid');
     }
     if (empty($courseid)) {
         $courseid = $key->instance;
 
     } else if ($courseid != $key->instance) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
     if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
 } else {
     if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     $key = new stdClass();
 }
@@ -67,12 +67,12 @@
 // Check if the user has at least one grade publishing capability.
 $plugins = grade_helper::get_plugins_import($course->id);
 if (!isset($plugins['keymanager'])) {
-    print_error('nopermissions');
+    throw new \moodle_exception('nopermissions');
 }
 
 // extra security check
 if (!empty($key->userid) and $USER->id != $key->userid) {
-    print_error('notownerofkey');
+    throw new \moodle_exception('notownerofkey');
 }
 
 $returnurl = $CFG->wwwroot.'/grade/import/keymanager.php?id='.$course->id;
diff --git a/grade/import/keymanager.php b/grade/import/keymanager.php
index decad005c78b2..a1e5c6fa1e8f2 100644
--- a/grade/import/keymanager.php
+++ b/grade/import/keymanager.php
@@ -31,7 +31,7 @@
 $PAGE->set_url('/grade/import/keymanager.php', array('id' => $id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -42,7 +42,7 @@
 // Check if the user has at least one grade publishing capability.
 $plugins = grade_helper::get_plugins_import($course->id);
 if (!isset($plugins['keymanager'])) {
-    print_error('nopermissions');
+    throw new \moodle_exception('nopermissions');
 }
 
 $actionbar = new \core_grades\output\import_key_manager_action_bar($context);
diff --git a/grade/import/xml/fetch.php b/grade/import/xml/fetch.php
index b12796849794c..12a0932a698bd 100644
--- a/grade/import/xml/fetch.php
+++ b/grade/import/xml/fetch.php
@@ -20,13 +20,13 @@
 
 $id = required_param('id', PARAM_INT); // course id
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_user_key_login('grade/import', $id); // we want different keys for each course
 
 if (empty($CFG->gradepublishing)) {
-    print_error('gradepubdisable');
+    throw new \moodle_exception('gradepubdisable');
 }
 
 $context = context_course::instance($id);
diff --git a/grade/import/xml/import.php b/grade/import/xml/import.php
index f12e799d6be41..6a4f136700ed8 100644
--- a/grade/import/xml/import.php
+++ b/grade/import/xml/import.php
@@ -30,7 +30,7 @@
 $PAGE->set_url($url);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
@@ -48,7 +48,7 @@
 
 $text = download_file_content($gradesurl);
 if ($text === false) {
-    print_error('cannotreadfile', 'error',
+    throw new \moodle_exception('cannotreadfile', 'error',
             $CFG->wwwroot . '/grade/import/xml/index.php?id=' . $id, $gradesurl);
 }
 
@@ -63,7 +63,7 @@
             echo 'ok';
             die;
         } else {
-            print_error('cannotimportgrade'); //TODO: localize
+            throw new \moodle_exception('cannotimportgrade'); // TODO: localize.
         }
 
     } else {
@@ -76,6 +76,6 @@
     }
 
 } else {
-    print_error('errorduringimport', 'gradeimport_xml',
+    throw new \moodle_exception('errorduringimport', 'gradeimport_xml',
             $CFG->wwwroot . '/grade/import/xml/index.php?id=' . $id, $error);
 }
diff --git a/grade/import/xml/index.php b/grade/import/xml/index.php
index 3be84baf7c6e1..9fbb2143e355d 100644
--- a/grade/import/xml/index.php
+++ b/grade/import/xml/index.php
@@ -25,7 +25,7 @@
 $PAGE->set_pagelayout('admin');
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/report/grader/ajax_callbacks.php b/grade/report/grader/ajax_callbacks.php
index de6bf8d288177..dbf512ea0cc75 100644
--- a/grade/report/grader/ajax_callbacks.php
+++ b/grade/report/grader/ajax_callbacks.php
@@ -37,7 +37,7 @@
 
 /// basic access checks
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 $context = context_course::instance($course->id);
 require_login($course);
@@ -52,7 +52,7 @@
         if (!empty($userid) && !empty($itemid) && $newvalue !== false && !empty($type)) {
             // Save the grade or feedback
             if (!$grade_item = grade_item::fetch(array('id'=>$itemid, 'courseid'=>$courseid))) { // we must verify course id here!
-                print_error('invalidgradeitemid');
+                throw new \moodle_exception('invalidgradeitemid');
             }
 
             /**
diff --git a/grade/report/grader/index.php b/grade/report/grader/index.php
index f294c0a9d8519..785e2efbe21cf 100644
--- a/grade/report/grader/index.php
+++ b/grade/report/grader/index.php
@@ -49,7 +49,7 @@
 
 // basic access checks
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login($course);
 $context = context_course::instance($course->id);
diff --git a/grade/report/grader/lib.php b/grade/report/grader/lib.php
index c4b49ee544824..c7ee6659a0c19 100644
--- a/grade/report/grader/lib.php
+++ b/grade/report/grader/lib.php
@@ -257,7 +257,7 @@ public function process_data($data) {
                     }
 
                     if (!$gradeitem = grade_item::fetch(array('id'=>$itemid, 'courseid'=>$this->courseid))) {
-                        print_error('invalidgradeitemid');
+                        throw new \moodle_exception('invalidgradeitemid');
                     }
 
                     // Pre-process grade
diff --git a/grade/report/grader/preferences.php b/grade/report/grader/preferences.php
index c20965c5c2a36..e9e4e4c95cedb 100644
--- a/grade/report/grader/preferences.php
+++ b/grade/report/grader/preferences.php
@@ -35,7 +35,7 @@
 /// Make sure they can even access this course
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/report/grader/quickedit_item.php b/grade/report/grader/quickedit_item.php
index 2a9741de50996..85aaa61dc65fb 100644
--- a/grade/report/grader/quickedit_item.php
+++ b/grade/report/grader/quickedit_item.php
@@ -44,11 +44,11 @@
 
 /// basic access checks
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if (!$item = $DB->get_record('grade_items', array('id' => $itemid))) {
-    print_error('noitemid', 'grades');
+    throw new \moodle_exception('noitemid', 'grades');
 }
 
 require_login($course);
diff --git a/grade/report/index.php b/grade/report/index.php
index 261c27717394f..bb647698b2fe6 100644
--- a/grade/report/index.php
+++ b/grade/report/index.php
@@ -30,7 +30,7 @@
 
 /// basic access checks
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login($course);
 $context = context_course::instance($course->id);
@@ -45,7 +45,7 @@
 }
 
 if (empty($reports)) {
-    print_error('noreports', 'debug', $CFG->wwwroot.'/course/view.php?id='.$course->id);
+    throw new \moodle_exception('noreports', 'debug', $CFG->wwwroot.'/course/view.php?id='.$course->id);
 }
 
 if (!isset($USER->grade_last_report)) {
diff --git a/grade/report/lib.php b/grade/report/lib.php
index 6fa0512f5bb94..2dbd0fc18b3be 100644
--- a/grade/report/lib.php
+++ b/grade/report/lib.php
@@ -165,7 +165,7 @@ public function __construct($courseid, $gpr, $context, $page=null) {
         global $CFG, $COURSE, $DB;
 
         if (empty($CFG->gradebookroles)) {
-            print_error('norolesdefined', 'grades');
+            throw new \moodle_exception('norolesdefined', 'grades');
         }
 
         $this->courseid  = $courseid;
diff --git a/grade/report/outcomes/index.php b/grade/report/outcomes/index.php
index 605a0233d6e11..7778a8a4a0e5d 100644
--- a/grade/report/outcomes/index.php
+++ b/grade/report/outcomes/index.php
@@ -31,7 +31,7 @@
 $PAGE->set_url('/grade/report/outcomes/index.php', array('id'=>$courseid));
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/grade/report/overview/index.php b/grade/report/overview/index.php
index 62c2cdcf6d866..ae8668d2d966d 100644
--- a/grade/report/overview/index.php
+++ b/grade/report/overview/index.php
@@ -33,7 +33,7 @@
 $PAGE->set_url(new moodle_url('/grade/report/overview/index.php', array('id' => $courseid, 'userid' => $userid)));
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login(null, false);
 $PAGE->set_course($course);
@@ -52,7 +52,7 @@
 
 } else {
     if (!$DB->get_record('user', array('id'=>$userid, 'deleted'=>0)) or isguestuser($userid)) {
-        print_error('invaliduserid');
+        throw new \moodle_exception('invaliduserid');
     }
     $personalcontext = context_user::instance($userid);
 }
@@ -75,7 +75,7 @@
 
 if (!$access) {
     // no access to grades!
-    print_error('nopermissiontoviewgrades', 'error',  $CFG->wwwroot.'/course/view.php?id='.$courseid);
+    throw new \moodle_exception('nopermissiontoviewgrades', 'error',  $CFG->wwwroot.'/course/view.php?id='.$courseid);
 }
 
 /// return tracking object
diff --git a/grade/report/singleview/index.php b/grade/report/singleview/index.php
index 9211b8aa67e97..0de0f0f66ac73 100644
--- a/grade/report/singleview/index.php
+++ b/grade/report/singleview/index.php
@@ -61,13 +61,13 @@
 $PAGE->set_pagelayout('incourse');
 
 if (!$course = $DB->get_record('course', $courseparams)) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
 
 if (!in_array($itemtype, gradereport_singleview::valid_screens())) {
-    print_error('notvalid', 'gradereport_singleview', '', $itemtype);
+    throw new \moodle_exception('notvalid', 'gradereport_singleview', '', $itemtype);
 }
 
 $context = context_course::instance($course->id);
diff --git a/grade/report/user/index.php b/grade/report/user/index.php
index 61f95afc70c65..9b58313ed693c 100644
--- a/grade/report/user/index.php
+++ b/grade/report/user/index.php
@@ -41,7 +41,7 @@
 
 /// basic access checks
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login($course);
 $PAGE->set_pagelayout('report');
@@ -54,7 +54,7 @@
 
 } else {
     if (!$DB->get_record('user', array('id'=>$userid, 'deleted'=>0)) or isguestuser($userid)) {
-        print_error('invaliduser');
+        throw new \moodle_exception('invaliduser');
     }
 }
 
@@ -74,7 +74,7 @@
 
 if (!$access) {
     // no access to grades!
-    print_error('nopermissiontoviewgrades', 'error',  $CFG->wwwroot.'/course/view.php?id='.$courseid);
+    throw new \moodle_exception('nopermissiontoviewgrades', 'error',  $CFG->wwwroot.'/course/view.php?id='.$courseid);
 }
 
 /// return tracking object
diff --git a/group/assign.php b/group/assign.php
index d31584d1c8bef..d3c37c7cc0986 100644
--- a/group/assign.php
+++ b/group/assign.php
@@ -31,11 +31,11 @@
 $PAGE->set_url('/group/assign.php', array('id'=>$groupingid));
 
 if (!$grouping = $DB->get_record('groupings', array('id'=>$groupingid))) {
-    print_error('invalidgroupid');
+    throw new \moodle_exception('invalidgroupid');
 }
 
 if (!$course = $DB->get_record('course', array('id'=>$grouping->courseid))) {
-    print_error('invalidcourse');
+    throw new \moodle_exception('invalidcourse');
 }
 $courseid = $course->id;
 
diff --git a/group/autogroup.php b/group/autogroup.php
index 2596021659cbc..5b85e56e54a6a 100644
--- a/group/autogroup.php
+++ b/group/autogroup.php
@@ -35,7 +35,7 @@
 $PAGE->set_url('/group/autogroup.php', array('courseid' => $courseid));
 
 if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 // Make sure that the user has permissions to manage groups.
@@ -83,7 +83,7 @@
         case 'idnumber':
             $orderby = 'idnumber'; break;
         default:
-            print_error('unknoworder');
+            throw new \moodle_exception('unknoworder');
     }
     $source = array();
     if ($data->cohortid) {
diff --git a/group/delete.php b/group/delete.php
index 88430a54ead9e..8ed752b9e5835 100644
--- a/group/delete.php
+++ b/group/delete.php
@@ -36,7 +36,7 @@
 
 // Make sure course is OK and user has access to manage groups
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login($course);
 $context = context_course::instance($course->id);
@@ -48,13 +48,13 @@
 $groupnames = array();
 foreach($groupidarray as $groupid) {
     if (!$group = $DB->get_record('groups', array('id' => $groupid))) {
-        print_error('invalidgroupid');
+        throw new \moodle_exception('invalidgroupid');
     }
     if (!empty($group->idnumber) && !$changeidnumber) {
-        print_error('grouphasidnumber', '', '', $group->name);
+        throw new \moodle_exception('grouphasidnumber', '', '', $group->name);
     }
     if ($courseid != $group->courseid) {
-        print_error('groupunknown', '', '', $group->courseid);
+        throw new \moodle_exception('groupunknown', '', '', $group->courseid);
     }
     $groupnames[] = format_string($group->name);
 }
@@ -62,12 +62,12 @@
 $returnurl='index.php?id='.$course->id;
 
 if(count($groupidarray)==0) {
-    print_error('errorselectsome','group',$returnurl);
+    throw new \moodle_exception('errorselectsome', 'group', $returnurl);
 }
 
 if ($confirm && data_submitted()) {
     if (!confirm_sesskey() ) {
-        print_error('confirmsesskeybad','error',$returnurl);
+        throw new \moodle_exception('confirmsesskeybad', 'error', $returnurl);
     }
 
     foreach($groupidarray as $groupid) {
diff --git a/group/group.php b/group/group.php
index 9b966b787649d..311e746a2d31a 100644
--- a/group/group.php
+++ b/group/group.php
@@ -43,22 +43,22 @@
 
 if ($id) {
     if (!$group = $DB->get_record('groups', array('id'=>$id))) {
-        print_error('invalidgroupid');
+        throw new \moodle_exception('invalidgroupid');
     }
     if (empty($courseid)) {
         $courseid = $group->courseid;
 
     } else if ($courseid != $group->courseid) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
     if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
 } else {
     if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     $group = new stdClass();
     $group->courseid = $course->id;
diff --git a/group/grouping.php b/group/grouping.php
index 16bd02d426c63..ec4d139862965 100644
--- a/group/grouping.php
+++ b/group/grouping.php
@@ -36,25 +36,25 @@
 if ($id) {
     $url->param('id', $id);
     if (!$grouping = $DB->get_record('groupings', array('id'=>$id))) {
-        print_error('invalidgroupid');
+        throw new \moodle_exception('invalidgroupid');
     }
     $grouping->description = clean_text($grouping->description);
     if (empty($courseid)) {
         $courseid = $grouping->courseid;
     } else if ($courseid != $grouping->courseid) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     } else {
         $url->param('courseid', $courseid);
     }
 
     if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
 } else {
     $url->param('courseid', $courseid);
     if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     $grouping = new stdClass();
     $grouping->courseid = $course->id;
@@ -76,7 +76,7 @@
 
 if ($id and $delete) {
     if (!empty($grouping->idnumber) && !has_capability('moodle/course:changeidnumber', $context)) {
-        print_error('groupinghasidnumber', '', '', $grouping->name);
+        throw new \moodle_exception('groupinghasidnumber', '', '', $grouping->name);
     }
     if (!$confirm) {
         $PAGE->set_title(get_string('deletegrouping', 'group'));
@@ -94,7 +94,7 @@
         if (groups_delete_grouping($id)) {
             redirect($returnurl);
         } else {
-            print_error('erroreditgrouping', 'group', $returnurl);
+            throw new \moodle_exception('erroreditgrouping', 'group', $returnurl);
         }
     }
 }
diff --git a/group/groupings.php b/group/groupings.php
index 7ff87f7626de1..a03eeb6fa64e8 100644
--- a/group/groupings.php
+++ b/group/groupings.php
@@ -31,7 +31,7 @@
 $PAGE->set_url('/group/groupings.php', array('id'=>$courseid));
 
 if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/group/import.php b/group/import.php
index b50f880d7389a..b6c027d95a86e 100644
--- a/group/import.php
+++ b/group/import.php
@@ -69,11 +69,11 @@
     $readcount = $csvimport->load_csv_content($text, $encoding, $delimiter);
 
     if ($readcount === false) {
-        print_error('csvfileerror', 'error', $PAGE->url, $csvimport->get_error());
+        throw new \moodle_exception('csvfileerror', 'error', $PAGE->url, $csvimport->get_error());
     } else if ($readcount == 0) {
-        print_error('csvemptyfile', 'error', $PAGE->url, $csvimport->get_error());
+        throw new \moodle_exception('csvemptyfile', 'error', $PAGE->url, $csvimport->get_error());
     } else if ($readcount == 1) {
-        print_error('csvnodata', 'error', $PAGE->url);
+        throw new \moodle_exception('csvnodata', 'error', $PAGE->url);
     }
 
     $csvimport->init();
@@ -100,7 +100,7 @@
     foreach ($header as $i => $h) {
         $h = trim($h); $header[$i] = $h; // remove whitespace
         if (!(isset($required[$h]) or isset($optionalDefaults[$h]) or isset($optional[$h]))) {
-                print_error('invalidfieldname', 'error', $PAGE->url, $h);
+                throw new \moodle_exception('invalidfieldname', 'error', $PAGE->url, $h);
             }
         if (isset($required[$h])) {
             $required[$h] = 2;
@@ -109,7 +109,7 @@
     // check for required fields
     foreach ($required as $key => $value) {
         if ($value < 2) {
-            print_error('fieldrequired', 'error', $PAGE->url, $key);
+            throw new \moodle_exception('fieldrequired', 'error', $PAGE->url, $key);
         }
     }
     $linenum = 2; // since header is line 1
@@ -130,7 +130,7 @@
             foreach ($record as $name => $value) {
                 // check for required values
                 if (isset($required[$name]) and !$value) {
-                    print_error('missingfield', 'error', $PAGE->url, $name);
+                    throw new \moodle_exception('missingfield', 'error', $PAGE->url, $name);
                 } else if ($name == "groupname") {
                     $newgroup->name = $value;
                 } else {
diff --git a/group/index.php b/group/index.php
index 3f79cb229277a..67654cacef3b4 100644
--- a/group/index.php
+++ b/group/index.php
@@ -70,7 +70,7 @@
         case 'showgroupsettingsform':
         case 'showaddmembersform':
         case 'updatemembers':
-            print_error('errorselectone', 'group', $returnurl);
+            throw new \moodle_exception('errorselectone', 'group', $returnurl);
     }
 }
 
@@ -120,7 +120,7 @@
 
     case 'deletegroup':
         if (count($groupids) == 0) {
-            print_error('errorselectsome','group',$returnurl);
+            throw new \moodle_exception('errorselectsome', 'group', $returnurl);
         }
         $groupidlist = implode(',', $groupids);
         redirect(new moodle_url('/group/delete.php', array('courseid'=>$courseid, 'groups'=>$groupidlist)));
@@ -156,7 +156,7 @@
         break;
 
     default: //ERROR.
-        print_error('unknowaction', '', $returnurl);
+        throw new \moodle_exception('unknowaction', '', $returnurl);
         break;
 }
 
@@ -278,7 +278,7 @@ function groups_param_action($prefix = 'act_') {
     }
     if ($action && !preg_match('/^\w+$/', $action)) {
         $action = false;
-        print_error('unknowaction');
+        throw new \moodle_exception('unknowaction');
     }
     ///if (debugging()) echo 'Debug: '.$action;
     return $action;
diff --git a/group/members.php b/group/members.php
index f089e3275b0b5..1d854e7fb04da 100644
--- a/group/members.php
+++ b/group/members.php
@@ -55,7 +55,7 @@
     if (!empty($userstoadd)) {
         foreach ($userstoadd as $user) {
             if (!groups_add_member($groupid, $user->id)) {
-                print_error('erroraddremoveuser', 'group', $returnurl);
+                throw new \moodle_exception('erroraddremoveuser', 'group', $returnurl);
             }
             $groupmembersselector->invalidate_selected_users();
             $potentialmembersselector->invalidate_selected_users();
@@ -68,11 +68,11 @@
     if (!empty($userstoremove)) {
         foreach ($userstoremove as $user) {
             if (!groups_remove_member_allowed($groupid, $user->id)) {
-                print_error('errorremovenotpermitted', 'group', $returnurl,
+                throw new \moodle_exception('errorremovenotpermitted', 'group', $returnurl,
                         $user->fullname);
             }
             if (!groups_remove_member($groupid, $user->id)) {
-                print_error('erroraddremoveuser', 'group', $returnurl);
+                throw new \moodle_exception('erroraddremoveuser', 'group', $returnurl);
             }
             $groupmembersselector->invalidate_selected_users();
             $potentialmembersselector->invalidate_selected_users();
diff --git a/group/overview.php b/group/overview.php
index 392bcdf341376..02b53f6b0a89a 100644
--- a/group/overview.php
+++ b/group/overview.php
@@ -39,7 +39,7 @@
 $rooturl   = $CFG->wwwroot.'/group/overview.php?id='.$courseid;
 
 if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-    print_error('invalidcourse');
+    throw new \moodle_exception('invalidcourse');
 }
 
 $url = new moodle_url('/group/overview.php', array('id'=>$courseid));
diff --git a/h5p/classes/editor.php b/h5p/classes/editor.php
index 33df1f6f1788d..feb3fe895e7ac 100644
--- a/h5p/classes/editor.php
+++ b/h5p/classes/editor.php
@@ -104,7 +104,7 @@ public function set_content(int $id): void {
         // Load the present content.
         $this->oldcontent = $this->core->loadContent($id);
         if ($this->oldcontent === null) {
-            print_error('invalidelementid');
+            throw new \moodle_exception('invalidelementid');
         }
 
         // Identify the content type library.
@@ -115,7 +115,7 @@ public function set_content(int $id): void {
         $fs = get_file_storage();
         $oldfile = $fs->get_file_by_hash($pathnamehash);
         if (!$oldfile) {
-            print_error('invalidelementid');
+            throw new \moodle_exception('invalidelementid');
         }
         $this->set_filearea(
             $oldfile->get_contextid(),
diff --git a/iplookup/index.php b/iplookup/index.php
index c285ee7916954..19f30cbe66d83 100644
--- a/iplookup/index.php
+++ b/iplookup/index.php
@@ -49,11 +49,11 @@
 $note = array();
 
 if (cleanremoteaddr($ip) === false) {
-    print_error('invalidipformat', 'error');
+    throw new \moodle_exception('invalidipformat', 'error');
 }
 
 if (!ip_is_public($ip)) {
-    print_error('iplookupprivate', 'error');
+    throw new \moodle_exception('iplookupprivate', 'error');
 }
 
 $info = iplookup_find_location($ip);
diff --git a/lib/accesslib.php b/lib/accesslib.php
index e4e7dbf311b1c..bf7e1f7d6ab00 100644
--- a/lib/accesslib.php
+++ b/lib/accesslib.php
@@ -1194,7 +1194,7 @@ function assign_legacy_capabilities($capability, $legacyperms) {
         }
 
         if (!array_key_exists($type, $archetypes)) {
-            print_error('invalidlegacy', '', '', $type);
+            throw new \moodle_exception('invalidlegacy', '', '', $type);
         }
 
         if ($roles = get_archetype_roles($type)) {
@@ -2385,7 +2385,8 @@ function capabilities_cleanup($component, $newcapdef = null) {
                 if ($roles = get_roles_with_capability($cachedcap->name)) {
                     foreach ($roles as $role) {
                         if (!unassign_capability($cachedcap->name, $role->id)) {
-                            print_error('cannotunassigncap', 'error', '', (object)array('cap'=>$cachedcap->name, 'role'=>$role->name));
+                            throw new \moodle_exception('cannotunassigncap', 'error', '',
+                                (object)array('cap' => $cachedcap->name, 'role' => $role->name));
                         }
                     }
                 }
diff --git a/lib/adminlib.php b/lib/adminlib.php
index d06f99977dc37..600322779356d 100644
--- a/lib/adminlib.php
+++ b/lib/adminlib.php
@@ -8814,15 +8814,15 @@ function admin_externalpage_setup($section, $extrabutton = '', array $extraurlpa
         if (!$hassiteconfig) {
             // The requested section could depend on a different capability
             // but most likely the user has inadequate capabilities
-            print_error('accessdenied', 'admin');
+            throw new \moodle_exception('accessdenied', 'admin');
         } else {
-            print_error('sectionerror', 'admin', "$CFG->wwwroot/$CFG->admin/");
+            throw new \moodle_exception('sectionerror', 'admin', "$CFG->wwwroot/$CFG->admin/");
         }
     }
 
     // this eliminates our need to authenticate on the actual pages
     if (!$extpage->check_access()) {
-        print_error('accessdenied', 'admin');
+        throw new \moodle_exception('accessdenied', 'admin');
         die;
     }
 
diff --git a/lib/ajax/setuserpref.php b/lib/ajax/setuserpref.php
index 77dc8191ab197..a960a288f7896 100644
--- a/lib/ajax/setuserpref.php
+++ b/lib/ajax/setuserpref.php
@@ -30,13 +30,13 @@
 
 // Check access.
 if (!confirm_sesskey()) {
-    print_error('invalidsesskey');
+    throw new \moodle_exception('invalidsesskey');
 }
 
 // Get the name of the preference to update, and check it is allowed.
 $name = required_param('pref', PARAM_RAW);
 if (!isset($USER->ajax_updatable_user_prefs[$name])) {
-    print_error('notallowedtoupdateprefremotely');
+    throw new \moodle_exception('notallowedtoupdateprefremotely');
 }
 
 // Get and the value.
@@ -44,7 +44,7 @@
 
 // Update
 if (!set_user_preference($name, $value)) {
-    print_error('errorsettinguserpref');
+    throw new \moodle_exception('errorsettinguserpref');
 }
 
 echo 'OK';
diff --git a/lib/authlib.php b/lib/authlib.php
index 54ffa3c044392..be63b37420d5f 100644
--- a/lib/authlib.php
+++ b/lib/authlib.php
@@ -133,7 +133,7 @@ class auth_plugin_base {
      * @return bool Authentication success or failure.
      */
     function user_login($username, $password) {
-        print_error('mustbeoveride', 'debug', '', 'user_login()' );
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'user_login()' );
     }
 
     /**
@@ -302,7 +302,7 @@ function can_signup() {
      */
     function user_signup($user, $notify=true) {
         //override when can signup
-        print_error('mustbeoveride', 'debug', '', 'user_signup()' );
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'user_signup()' );
     }
 
     /**
@@ -335,7 +335,7 @@ function can_confirm() {
      */
     function user_confirm($username, $confirmsecret) {
         //override when can confirm
-        print_error('mustbeoveride', 'debug', '', 'user_confirm()' );
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'user_confirm()' );
     }
 
     /**
@@ -651,7 +651,7 @@ protected function update_user_record($username, $updatekeys = false, $triggerev
         $user = $DB->get_record('user', array('username' => $username, 'mnethostid' => $CFG->mnet_localhost_id));
         if (empty($user)) { // Trouble.
             error_log($this->errorlogtag . get_string('auth_usernotexist', 'auth', $username));
-            print_error('auth_usernotexist', 'auth', '', $username);
+            throw new \moodle_exception('auth_usernotexist', 'auth', '', $username);
             die;
         }
 
diff --git a/lib/completionlib.php b/lib/completionlib.php
index cd6edf242fc6e..eb8057da8dc77 100644
--- a/lib/completionlib.php
+++ b/lib/completionlib.php
@@ -360,7 +360,7 @@ public function get_completion($user_id, $criteriatype) {
         if (empty($completions)) {
             return false;
         } elseif (count($completions) > 1) {
-            print_error('multipleselfcompletioncriteria', 'completion');
+            throw new \moodle_exception('multipleselfcompletioncriteria', 'completion');
         }
 
         return $completions[0];
diff --git a/lib/componentlib.class.php b/lib/componentlib.class.php
index 858038d7e2ad7..680acae6e028f 100644
--- a/lib/componentlib.class.php
+++ b/lib/componentlib.class.php
@@ -76,9 +76,9 @@
  *                     $a = new stdClass();
  *                     $a->url = 'https://download.moodle.org/langpack/2.0/es.zip';
  *                     $a->dest= $CFG->dataroot.'/lang';
- *                     print_error($cd->get_error(), 'error', '', $a);
+ *                     throw new \moodle_exception($cd->get_error(), 'error', '', $a);
  *                 } else {
- *                     print_error($cd->get_error(), 'error');
+ *                     throw new \moodle_exception($cd->get_error(), 'error');
  *                 }
  *                 break;
  *             case COMPONENT_UPTODATE:
diff --git a/lib/ddllib.php b/lib/ddllib.php
index 7c5896124c0ec..bde2a81b2c045 100644
--- a/lib/ddllib.php
+++ b/lib/ddllib.php
@@ -70,7 +70,7 @@
 
 
 /**
- * DDL exception class, use instead of print_error() and "return false;" in ddl code.
+ * DDL exception class, use instead of throw new \moodle_exception() and "return false;" in ddl code.
  */
 class ddl_exception extends moodle_exception {
     /**
diff --git a/lib/deprecatedlib.php b/lib/deprecatedlib.php
index 033a53db49d5e..7c7a439922e4d 100644
--- a/lib/deprecatedlib.php
+++ b/lib/deprecatedlib.php
@@ -664,7 +664,7 @@ function groups_course_module_visible() {
  */
 function error() {
     throw new coding_exception('notlocalisederrormessage', 'error', $link, $message, 'error() is a removed, please call
-            print_error() instead of error()');
+            throw new \moodle_exception() instead of error()');
 }
 
 
@@ -3734,3 +3734,24 @@ function get_array_of_activities(int $courseid, bool $usecache = false): array {
         DEBUG_DEVELOPER);
     return course_modinfo::get_array_of_activities(get_course($courseid), $usecache);
 }
+
+/**
+ * Abort execution by throwing of a general exception,
+ * default exception handler displays the error message in most cases.
+ *
+ * @deprecated since Moodle 4.1
+ * @todo MDL-74484 Final deprecation in Moodle 4.5.
+ * @param string $errorcode The name of the language string containing the error message.
+ *      Normally this should be in the error.php lang file.
+ * @param string $module The language file to get the error message from.
+ * @param string $link The url where the user will be prompted to continue.
+ *      If no url is provided the user will be directed to the site index page.
+ * @param object $a Extra words and phrases that might be required in the error string
+ * @param string $debuginfo optional debugging information
+ * @return void, always throws exception!
+ */
+function print_error($errorcode, $module = 'error', $link = '', $a = null, $debuginfo = null) {
+    debugging("The function print_error() is deprecated. " .
+            "Please throw a new moodle_exception instance instead.", DEBUG_DEVELOPER);
+    throw new \moodle_exception($errorcode, $module, $link, $a, $debuginfo);
+}
diff --git a/lib/dml/pdo_moodle_database.php b/lib/dml/pdo_moodle_database.php
index 2fef5493c254b..2a0989fd5839a 100644
--- a/lib/dml/pdo_moodle_database.php
+++ b/lib/dml/pdo_moodle_database.php
@@ -527,7 +527,7 @@ public function set_field_select($table, $newfield, $newvalue, $select, array $p
                 break;
             default:
                 $this->lastError = __FILE__ . ' LINE: ' . __LINE__ . '.';
-                print_error(unknowparamtype, 'error', '', $this->lastError);
+                throw new \moodle_exception(unknowparamtype, 'error', '', $this->lastError);
             }
         }
         $sql = "UPDATE {{$table}} SET $newfield $select";
@@ -535,11 +535,11 @@ public function set_field_select($table, $newfield, $newvalue, $select, array $p
     }
 
     public function sql_concat() {
-        print_error('TODO');
+        throw new \moodle_exception('TODO');
     }
 
     public function sql_concat_join($separator="' '", $elements=array()) {
-        print_error('TODO');
+        throw new \moodle_exception('TODO');
     }
 
     /**
diff --git a/lib/dmllib.php b/lib/dmllib.php
index 1a2f51400c0a8..b7527e3060589 100644
--- a/lib/dmllib.php
+++ b/lib/dmllib.php
@@ -52,7 +52,7 @@
 define('MUST_EXIST', 2);
 
 /**
- * DML exception class, use instead of print_error() in dml code.
+ * DML exception class, use instead of throw new \moodle_exception() in dml code.
  *
  * @package    core
  * @category   dml
diff --git a/lib/editor/atto/autosave-ajax.php b/lib/editor/atto/autosave-ajax.php
index 65d13a271d901..28c13c35ee988 100644
--- a/lib/editor/atto/autosave-ajax.php
+++ b/lib/editor/atto/autosave-ajax.php
@@ -48,7 +48,7 @@
     foreach ($keys as $key => $type) {
         // Replicate required_param().
         if (!isset($actionparams[$key])) {
-            print_error('missingparam', '', '', $key);
+            throw new \moodle_exception('missingparam', '', '', $key);
         }
         $params[$key] = clean_param($actionparams[$key], $type);
     }
@@ -68,12 +68,12 @@
 
 require_login();
 if (isguestuser()) {
-    print_error('accessdenied', 'admin');
+    throw new \moodle_exception('accessdenied', 'admin');
 }
 require_sesskey();
 
 if (!in_array('atto', explode(',', get_config('core', 'texteditors')))) {
-    print_error('accessdenied', 'admin');
+    throw new \moodle_exception('accessdenied', 'admin');
 }
 
 $responses = array();
@@ -94,7 +94,7 @@
 
         $record = $DB->get_record('editor_atto_autosave', $params);
         if ($record && $record->pageinstance != $pageinstance) {
-            print_error('concurrent access from the same user is not supported');
+            throw new \moodle_exception('concurrent access from the same user is not supported');
             die();
         }
 
diff --git a/lib/editor/atto/plugins/equation/ajax.php b/lib/editor/atto/plugins/equation/ajax.php
index dc48f383f62a2..527a9df91be04 100644
--- a/lib/editor/atto/plugins/equation/ajax.php
+++ b/lib/editor/atto/plugins/equation/ajax.php
@@ -48,4 +48,4 @@
     die();
 }
 
-print_error('invalidarguments');
+throw new \moodle_exception('invalidarguments');
diff --git a/lib/editor/atto/plugins/managefiles/manage.php b/lib/editor/atto/plugins/managefiles/manage.php
index 5dd39a4948172..d22c837910ec3 100644
--- a/lib/editor/atto/plugins/managefiles/manage.php
+++ b/lib/editor/atto/plugins/managefiles/manage.php
@@ -54,7 +54,7 @@
 
 // Guests can never manage files.
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 $title = get_string('managefiles', 'atto_managefiles');
diff --git a/lib/editor/tinymce/plugins/loader.php b/lib/editor/tinymce/plugins/loader.php
index 537ac791d5333..c84bc54d546c9 100644
--- a/lib/editor/tinymce/plugins/loader.php
+++ b/lib/editor/tinymce/plugins/loader.php
@@ -41,7 +41,7 @@
 // path inside the plugin tinymce folder.
 $matches = array();
 if (!preg_match('~^/([a-z0-9_]+)/((?:[0-9.]+)|-1)(/.*)$~', $path, $matches)) {
-    print_error('filenotfound');
+    throw new \moodle_exception('filenotfound');
 }
 list($junk, $tinymceplugin, $version, $innerpath) = $matches;
 
@@ -52,7 +52,7 @@
 $pluginfolder = $CFG->dirroot . '/lib/editor/tinymce/plugins/' . $tinymceplugin;
 $file = $pluginfolder . '/tinymce' .$innerpath;
 if (!file_exists($file)) {
-    print_error('filenotfound');
+    throw new \moodle_exception('filenotfound');
 }
 
 // We don't actually care what the version number is but there is a special
diff --git a/lib/editor/tinymce/plugins/managefiles/manage.php b/lib/editor/tinymce/plugins/managefiles/manage.php
index 25db21e98f42d..b713defb47276 100644
--- a/lib/editor/tinymce/plugins/managefiles/manage.php
+++ b/lib/editor/tinymce/plugins/managefiles/manage.php
@@ -50,7 +50,7 @@
 }
 if (isguestuser()) {
     // Guests can never manage files.
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 $title = get_string('manageareafiles', 'tinymce_managefiles');
diff --git a/lib/filelib.php b/lib/filelib.php
index 8d11e3b63819d..2449a64766a75 100644
--- a/lib/filelib.php
+++ b/lib/filelib.php
@@ -368,7 +368,7 @@ function file_get_unused_draft_itemid() {
 
     if (isguestuser() or !isloggedin()) {
         // guests and not-logged-in users can not be allowed to upload anything!!!!!!
-        print_error('noguest');
+        throw new \moodle_exception('noguest');
     }
 
     $contextid = context_user::instance($USER->id)->id;
@@ -2137,7 +2137,8 @@ function send_file_not_found() {
     }
 
     send_header_404();
-    print_error('filenotfound', 'error', $CFG->wwwroot.'/course/view.php?id='.$COURSE->id); //this is not displayed on IIS??
+    throw new \moodle_exception('filenotfound', 'error',
+        $CFG->wwwroot.'/course/view.php?id='.$COURSE->id); // This is not displayed on IIS?
 }
 /**
  * Helper function to send correct 404 for server.
@@ -2372,7 +2373,7 @@ function send_temp_file($path, $filename, $pathisstring=false) {
     if (!$pathisstring) {
         if (!file_exists($path)) {
             send_header_404();
-            print_error('filenotfound', 'error', $CFG->wwwroot.'/');
+            throw new \moodle_exception('filenotfound', 'error', $CFG->wwwroot.'/');
         }
         // executed after normal finish or abort
         core_shutdown_manager::register_function('send_temp_file_finished', array($path));
@@ -4355,16 +4356,16 @@ function file_pluginfile($relativepath, $forcedownload, $preview = null, $offlin
     global $DB, $CFG, $USER;
     // relative path must start with '/'
     if (!$relativepath) {
-        print_error('invalidargorconf');
+        throw new \moodle_exception('invalidargorconf');
     } else if ($relativepath[0] != '/') {
-        print_error('pathdoesnotstartslash');
+        throw new \moodle_exception('pathdoesnotstartslash');
     }
 
     // extract relative path components
     $args = explode('/', ltrim($relativepath, '/'));
 
     if (count($args) < 3) { // always at least context, component and filearea
-        print_error('invalidarguments');
+        throw new \moodle_exception('invalidarguments');
     }
 
     $contextid = (int)array_shift($args);
@@ -4388,7 +4389,7 @@ function file_pluginfile($relativepath, $forcedownload, $preview = null, $offlin
         }
 
         if (empty($CFG->enableblogs)) {
-            print_error('siteblogdisable', 'blog');
+            throw new \moodle_exception('siteblogdisable', 'blog');
         }
 
         $entryid = (int)array_shift($args);
@@ -4398,7 +4399,7 @@ function file_pluginfile($relativepath, $forcedownload, $preview = null, $offlin
         if ($CFG->bloglevel < BLOG_GLOBAL_LEVEL) {
             require_login();
             if (isguestuser()) {
-                print_error('noguest');
+                throw new \moodle_exception('noguest');
             }
             if ($CFG->bloglevel == BLOG_USER_LEVEL) {
                 if ($USER->id != $entry->userid) {
diff --git a/lib/filestorage/zip_archive.php b/lib/filestorage/zip_archive.php
index beff0510badba..4c5953b342c0c 100644
--- a/lib/filestorage/zip_archive.php
+++ b/lib/filestorage/zip_archive.php
@@ -460,7 +460,7 @@ public function add_file_from_string($localname, $contents) {
             $this->close();
             $res = $this->open($this->archivepathname, file_archive::OPEN, $this->encoding);
             if ($res !== true) {
-                print_error('cannotopenzip');
+                throw new \moodle_exception('cannotopenzip');
             }
         }
         $this->usedmem += strlen($contents);
diff --git a/lib/form/filemanager.php b/lib/form/filemanager.php
index 59fb995ca964d..e333111d683ab 100644
--- a/lib/form/filemanager.php
+++ b/lib/form/filemanager.php
@@ -254,7 +254,7 @@ function toHtml() {
 
         // security - never ever allow guest/not logged in user to upload anything or use this element!
         if (isguestuser() or !isloggedin()) {
-            print_error('noguest');
+            throw new \moodle_exception('noguest');
         }
 
         if ($this->_flagFrozen) {
diff --git a/lib/formslib.php b/lib/formslib.php
index 7f5228987af37..7995f206d6d8c 100644
--- a/lib/formslib.php
+++ b/lib/formslib.php
@@ -312,7 +312,7 @@ function _process_submission($method) {
         // the _qf__.$this->_formname serves as a marker that form was actually submitted
         if (array_key_exists('_qf__'.$this->_formname, $submission) and $submission['_qf__'.$this->_formname] == 1) {
             if (!confirm_sesskey()) {
-                print_error('invalidsesskey');
+                throw new \moodle_exception('invalidsesskey');
             }
             $files = $_FILES;
         } else {
diff --git a/lib/grade/grade_category.php b/lib/grade/grade_category.php
index 3f96c3c6f0ebf..207f3fc1ceadc 100644
--- a/lib/grade/grade_category.php
+++ b/lib/grade/grade_category.php
@@ -359,7 +359,7 @@ public function delete($source=null) {
     public function insert($source = null, $isbulkupdate = false) {
 
         if (empty($this->courseid)) {
-            print_error('cannotinsertgrade');
+            throw new \moodle_exception('cannotinsertgrade');
         }
 
         if (empty($this->parent)) {
@@ -2369,11 +2369,11 @@ public function set_parent($parentid, $source=null) {
         }
 
         if ($parentid == $this->id) {
-            print_error('cannotassignselfasparent');
+            throw new \moodle_exception('cannotassignselfasparent');
         }
 
         if (empty($this->parent) and $this->is_course_category()) {
-            print_error('cannothaveparentcate');
+            throw new \moodle_exception('cannothaveparentcate');
         }
 
         // find parent and check course id
diff --git a/lib/grade/grade_grade.php b/lib/grade/grade_grade.php
index 7476ac4ce2809..ff6472e74f13c 100644
--- a/lib/grade/grade_grade.php
+++ b/lib/grade/grade_grade.php
@@ -768,7 +768,7 @@ public static function get_hiding_affected(&$grade_grades, &$grade_items) {
         global $CFG;
 
         if (count($grade_grades) !== count($grade_items)) {
-            print_error('invalidarraysize', 'debug', '', 'grade_grade::get_hiding_affected()!');
+            throw new \moodle_exception('invalidarraysize', 'debug', '', 'grade_grade::get_hiding_affected()!');
         }
 
         $dependson = array();
diff --git a/lib/grade/grade_item.php b/lib/grade/grade_item.php
index 7107563d9c312..1ad1778491213 100644
--- a/lib/grade/grade_item.php
+++ b/lib/grade/grade_item.php
@@ -507,7 +507,7 @@ public function insert($source = null, $isbulkupdate = false) {
         global $CFG, $DB;
 
         if (empty($this->courseid)) {
-            print_error('cannotinsertgrade');
+            throw new \moodle_exception('cannotinsertgrade');
         }
 
         // load scale if needed
@@ -1531,7 +1531,7 @@ public function get_description() {
      */
     public function set_parent($parentid, $updateaggregationfields = true) {
         if ($this->is_course_item() or $this->is_category_item()) {
-            print_error('cannotsetparentforcatoritem');
+            throw new \moodle_exception('cannotsetparentforcatoritem');
         }
 
         if ($this->categoryid == $parentid) {
diff --git a/lib/grade/grade_object.php b/lib/grade/grade_object.php
index 66a795452bdbb..ab2276a71a9c4 100644
--- a/lib/grade/grade_object.php
+++ b/lib/grade/grade_object.php
@@ -160,7 +160,7 @@ protected static function fetch_helper($table, $classname, $params) {
         if ($instances = grade_object::fetch_all_helper($table, $classname, $params)) {
             if (count($instances) > 1) {
                 // we should not tolerate any errors here - problems might appear later
-                print_error('morethanonerecordinfetch','debug');
+                throw new \moodle_exception('morethanonerecordinfetch', 'debug');
             }
             return reset($instances);
         } else {
diff --git a/lib/gradelib.php b/lib/gradelib.php
index 72d13e40564cb..8dc9ebd52040e 100644
--- a/lib/gradelib.php
+++ b/lib/gradelib.php
@@ -1152,7 +1152,7 @@ function grade_regrade_final_grades($courseid, $userid=null, $updated_item=null,
     if ($userid) {
         // one raw grade updated for one user
         if (empty($updated_item)) {
-            print_error("cannotbenull", 'debug', '', "updated_item");
+            throw new \moodle_exception("cannotbenull", 'debug', '', "updated_item");
         }
         if ($course_item->needsupdate) {
             $updated_item->force_regrading();
@@ -1352,7 +1352,7 @@ function grade_grab_course_grades($courseid, $modname=null, $userid=0) {
     }
 
     if (!$mods = core_component::get_plugin_list('mod') ) {
-        print_error('nomodules', 'debug');
+        throw new \moodle_exception('nomodules', 'debug');
     }
 
     foreach ($mods as $mod => $fullmod) {
diff --git a/lib/licenselib.php b/lib/licenselib.php
index 017ffc0337c13..f77e3b11e6e03 100644
--- a/lib/licenselib.php
+++ b/lib/licenselib.php
@@ -323,7 +323,7 @@ static public function disable($license) {
         global $CFG;
         // Site default license cannot be disabled!
         if ($license == $CFG->sitedefaultlicense) {
-            print_error('error');
+            throw new \moodle_exception('error');
         }
         if ($license = self::get_license_by_shortname($license)) {
             $license->enabled = self::LICENSE_DISABLED;
diff --git a/lib/listlib.php b/lib/listlib.php
index 67520aebbcd63..894a793cfc8b0 100644
--- a/lib/listlib.php
+++ b/lib/listlib.php
@@ -171,7 +171,7 @@ public function find_item($id, $suppresserror = false) {
         }
 
         if (!$suppresserror) {
-            print_error('listnoitem');
+            throw new \moodle_exception('listnoitem');
         }
         return null;
     }
@@ -324,7 +324,7 @@ public function move_item_up_down($direction, $id) {
                     $peers[$itemkey+1] = $id;
                     $peers[$itemkey] = $olditem;
                 } else {
-                    print_error('listcantmoveup');
+                    throw new \moodle_exception('listcantmoveup');
                 }
                 break;
 
@@ -334,7 +334,7 @@ public function move_item_up_down($direction, $id) {
                     $peers[$itemkey-1] = $id;
                     $peers[$itemkey] = $olditem;
                 } else {
-                    print_error('listcantmovedown');
+                    throw new \moodle_exception('listcantmovedown');
                 }
                 break;
         }
@@ -359,7 +359,7 @@ public function move_item_left($id) {
 
         $item = $this->find_item($id);
         if (!isset($item->parentlist->parentitem->parentlist)) {
-            print_error('listcantmoveleft');
+            throw new \moodle_exception('listcantmoveleft');
         } else {
             $newpeers = $this->get_items_peers($item->parentlist->parentitem->id);
             if (isset($item->parentlist->parentitem->parentlist->parentitem)) {
@@ -386,7 +386,7 @@ public function move_item_right($id) {
         $peers = $this->get_items_peers($id);
         $itemkey = array_search($id, $peers);
         if (!isset($peers[$itemkey-1])) {
-            print_error('listcantmoveright');
+            throw new \moodle_exception('listcantmoveright');
         } else {
             $DB->set_field($this->table, "parent", $peers[$itemkey-1], array("id"=>$peers[$itemkey]));
             $newparent = $this->find_item($peers[$itemkey-1]);
diff --git a/lib/moodlelib.php b/lib/moodlelib.php
index c83e9225b0d73..06ea43dd96661 100644
--- a/lib/moodlelib.php
+++ b/lib/moodlelib.php
@@ -589,7 +589,7 @@ function required_param($parname, $type) {
     } else if (isset($_GET[$parname])) {
         $param = $_GET[$parname];
     } else {
-        print_error('missingparam', '', '', $parname);
+        throw new \moodle_exception('missingparam', '', '', $parname);
     }
 
     if (is_array($param)) {
@@ -628,10 +628,10 @@ function required_param_array($parname, $type) {
     } else if (isset($_GET[$parname])) {
         $param = $_GET[$parname];
     } else {
-        print_error('missingparam', '', '', $parname);
+        throw new \moodle_exception('missingparam', '', '', $parname);
     }
     if (!is_array($param)) {
-        print_error('missingparam', '', '', $parname);
+        throw new \moodle_exception('missingparam', '', '', $parname);
     }
 
     $result = array();
@@ -1268,7 +1268,7 @@ function clean_param($param, $type) {
 
         default:
             // Doh! throw error, switched parameters in optional_param or another serious problem.
-            print_error("unknownparamtype", '', '', $type);
+            throw new \moodle_exception("unknownparamtype", '', '', $type);
     }
 }
 
@@ -2799,7 +2799,8 @@ function require_login($courseorid = null, $autologinguest = true, $cm = null, $
     if ($course->id != SITEID and \core\session\manager::is_loggedinas()) {
         if ($USER->loginascontext->contextlevel == CONTEXT_COURSE) {
             if ($USER->loginascontext->instanceid != $course->id) {
-                print_error('loginasonecourse', '', $CFG->wwwroot.'/course/view.php?id='.$USER->loginascontext->instanceid);
+                throw new \moodle_exception('loginasonecourse', '',
+                    $CFG->wwwroot.'/course/view.php?id='.$USER->loginascontext->instanceid);
             }
         }
     }
@@ -3264,17 +3265,17 @@ function validate_user_key($keyvalue, $script, $instance) {
     global $DB;
 
     if (!$key = $DB->get_record('user_private_key', array('script' => $script, 'value' => $keyvalue, 'instance' => $instance))) {
-        print_error('invalidkey');
+        throw new \moodle_exception('invalidkey');
     }
 
     if (!empty($key->validuntil) and $key->validuntil < time()) {
-        print_error('expiredkey');
+        throw new \moodle_exception('expiredkey');
     }
 
     if ($key->iprestriction) {
         $remoteaddr = getremoteaddr(null);
         if (empty($remoteaddr) or !address_in_subnet($remoteaddr, $key->iprestriction)) {
-            print_error('ipmismatch');
+            throw new \moodle_exception('ipmismatch');
         }
     }
     return $key;
@@ -3294,7 +3295,7 @@ function require_user_key_login($script, $instance = null, $keyvalue = null) {
     global $DB;
 
     if (!NO_MOODLE_COOKIES) {
-        print_error('sessioncookiesdisable');
+        throw new \moodle_exception('sessioncookiesdisable');
     }
 
     // Extra safety.
@@ -3307,7 +3308,7 @@ function require_user_key_login($script, $instance = null, $keyvalue = null) {
     $key = validate_user_key($keyvalue, $script, $instance);
 
     if (!$user = $DB->get_record('user', array('id' => $key->userid))) {
-        print_error('invaliduserid');
+        throw new \moodle_exception('invaliduserid');
     }
 
     core_user::require_active_user($user, true, true);
@@ -3788,7 +3789,7 @@ function get_auth_plugin($auth) {
 
     // Check the plugin exists first.
     if (! exists_auth_plugin($auth)) {
-        print_error('authpluginnotfound', 'debug', '', $auth);
+        throw new \moodle_exception('authpluginnotfound', 'debug', '', $auth);
     }
 
     // Return auth plugin instance.
@@ -4643,7 +4644,7 @@ function complete_user_login($user) {
                 redirect($CFG->wwwroot.'/login/change_password.php');
             }
         } else {
-            print_error('nopasswordchangeforced', 'auth');
+            throw new \moodle_exception('nopasswordchangeforced', 'auth');
         }
     }
     return $USER;
@@ -6428,7 +6429,7 @@ function reset_password_and_mail($user) {
     $newpassword = generate_password();
 
     if (!$userauth->user_update_password($user, $newpassword)) {
-        print_error("cannotsetpassword");
+        throw new \moodle_exception("cannotsetpassword");
     }
 
     $a = new stdClass();
diff --git a/lib/outputrenderers.php b/lib/outputrenderers.php
index 50d6abbb8312f..153c6b49022a3 100644
--- a/lib/outputrenderers.php
+++ b/lib/outputrenderers.php
@@ -2902,9 +2902,8 @@ public function error_text($message) {
     /**
      * Do not call this function directly.
      *
-     * To terminate the current script with a fatal error, call the {@link print_error}
-     * function, or throw an exception. Doing either of those things will then call this
-     * function to display the error, before terminating the execution.
+     * To terminate the current script with a fatal error, throw an exception.
+     * Doing this will then call this function to display the error, before terminating the execution.
      *
      * @param string $message The message to output
      * @param string $moreinfourl URL where more info can be found about the error
diff --git a/lib/sessionlib.php b/lib/sessionlib.php
index 59e2e6aa51f35..af4c0a6f6bf0c 100644
--- a/lib/sessionlib.php
+++ b/lib/sessionlib.php
@@ -82,7 +82,7 @@ function confirm_sesskey($sesskey=NULL) {
  */
 function require_sesskey() {
     if (!confirm_sesskey()) {
-        print_error('invalidsesskey');
+        throw new \moodle_exception('invalidsesskey');
     }
 }
 
diff --git a/lib/setup.php b/lib/setup.php
index a5a22fda3462a..a49539753ffa3 100644
--- a/lib/setup.php
+++ b/lib/setup.php
@@ -569,7 +569,7 @@
 // Put $OUTPUT in place, so errors can be displayed.
 $OUTPUT = new bootstrap_renderer();
 
-// set handler for uncaught exceptions - equivalent to print_error() call
+// Set handler for uncaught exceptions - equivalent to throw new \moodle_exception() call.
 if (!PHPUNIT_TEST or PHPUNIT_UTIL) {
     set_exception_handler('default_exception_handler');
     set_error_handler('default_error_handler', E_ALL | E_STRICT);
@@ -722,7 +722,7 @@
     if ($CFG->upgraderunning < time()) {
         unset_config('upgraderunning');
     } else {
-        print_error('upgraderunning');
+        throw new \moodle_exception('upgraderunning');
     }
 }
 
@@ -734,7 +734,7 @@
 
 // detect unsupported upgrade jump as soon as possible - do not change anything, do not use system functions
 if (!empty($CFG->version) and $CFG->version < 2007101509) {
-    print_error('upgraderequires19', 'error');
+    throw new \moodle_exception('upgraderequires19', 'error');
     die;
 }
 
diff --git a/lib/setuplib.php b/lib/setuplib.php
index 47e9a90b5286d..2cdd8f22e1a1f 100644
--- a/lib/setuplib.php
+++ b/lib/setuplib.php
@@ -480,23 +480,6 @@ function is_early_init($backtrace) {
     return false;
 }
 
-/**
- * Abort execution by throwing of a general exception,
- * default exception handler displays the error message in most cases.
- *
- * @param string $errorcode The name of the language string containing the error message.
- *      Normally this should be in the error.php lang file.
- * @param string $module The language file to get the error message from.
- * @param string $link The url where the user will be prompted to continue.
- *      If no url is provided the user will be directed to the site index page.
- * @param object $a Extra words and phrases that might be required in the error string
- * @param string $debuginfo optional debugging information
- * @return void, always throws exception!
- */
-function print_error($errorcode, $module = 'error', $link = '', $a = null, $debuginfo = null) {
-    throw new moodle_exception($errorcode, $module, $link, $a, $debuginfo);
-}
-
 /**
  * Returns detailed information about specified exception.
  * @param exception $ex
@@ -760,7 +743,7 @@ function setup_validate_php_configuration() {
    // this must be very fast - no slow checks here!!!
 
    if (ini_get_bool('session.auto_start')) {
-       print_error('sessionautostartwarning', 'admin');
+        throw new \moodle_exception('sessionautostartwarning', 'admin');
    }
 }
 
@@ -846,7 +829,7 @@ function initialise_fullme() {
 
     // Detect common config error.
     if (substr($CFG->wwwroot, -1) == '/') {
-        print_error('wwwrootslash', 'error');
+        throw new \moodle_exception('wwwrootslash', 'error');
     }
 
     if (CLI_SCRIPT) {
@@ -913,7 +896,7 @@ function initialise_fullme() {
     if (empty($CFG->sslproxy)) {
         if ($rurl['scheme'] === 'http' and $wwwroot['scheme'] === 'https') {
             if (defined('REQUIRE_CORRECT_ACCESS') && REQUIRE_CORRECT_ACCESS) {
-                print_error('sslonlyaccess', 'error');
+                throw new \moodle_exception('sslonlyaccess', 'error');
             } else {
                 redirect($CFG->wwwroot, get_string('wwwrootmismatch', 'error', $CFG->wwwroot), 3);
             }
@@ -931,7 +914,7 @@ function initialise_fullme() {
     // with two different addresses in intranet and Internet.
     // Port forwarding is still allowed!
     if (!empty($CFG->reverseproxy) && $rurl['host'] === $wwwroot['host'] && (empty($wwwroot['port']) || $rurl['port'] === $wwwroot['port'])) {
-        print_error('reverseproxyabused', 'error');
+        throw new \moodle_exception('reverseproxyabused', 'error');
     }
 
     $hostandport = $rurl['scheme'] . '://' . $wwwroot['host'];
diff --git a/lib/upgrade.txt b/lib/upgrade.txt
index d3641b37ffe0b..b4dc478e93d31 100644
--- a/lib/upgrade.txt
+++ b/lib/upgrade.txt
@@ -31,6 +31,7 @@ information provided here is intended especially for developers.
   plugin developers to not use this attribute for Moodle versions 4.0 and below in order to avoid this problem.
 * Added $CFG->proxylogunsafe and proxyfixunsafe to detect code which doesn't honor the proxy config
 * Function admin_externalpage_setup() now has additional option 'nosearch' allowing to remove Site administration search form.
+* The function print_error has been deprecated. Kindly use moodle_exception.
 
 === 4.0 ===
 
diff --git a/lib/upgradelib.php b/lib/upgradelib.php
index acd4adcc42ea0..f131719cf2807 100644
--- a/lib/upgradelib.php
+++ b/lib/upgradelib.php
@@ -238,7 +238,7 @@ function upgrade_set_timeout($max_execution_time=300) {
             $upgraderunning = 0;
         } else {
             // web upgrade not running or aborted
-            print_error('upgradetimedout', 'admin', "$CFG->wwwroot/$CFG->admin/");
+            throw new \moodle_exception('upgradetimedout', 'admin', "$CFG->wwwroot/$CFG->admin/");
         }
     }
 
@@ -333,7 +333,7 @@ function upgrade_mod_savepoint($result, $version, $modname, $allowabort=true) {
     $dbversion = $DB->get_field('config_plugins', 'value', array('plugin'=>$component, 'name'=>'version'));
 
     if (!$module = $DB->get_record('modules', array('name'=>$modname))) {
-        print_error('modulenotexist', 'debug', '', $modname);
+        throw new \moodle_exception('modulenotexist', 'debug', '', $modname);
     }
 
     if ($dbversion >= $version) {
@@ -379,7 +379,7 @@ function upgrade_block_savepoint($result, $version, $blockname, $allowabort=true
     $dbversion = $DB->get_field('config_plugins', 'value', array('plugin'=>$component, 'name'=>'version'));
 
     if (!$block = $DB->get_record('block', array('name'=>$blockname))) {
-        print_error('blocknotexist', 'debug', '', $blockname);
+        throw new \moodle_exception('blocknotexist', 'debug', '', $blockname);
     }
 
     if ($dbversion >= $version) {
diff --git a/login/change_password.php b/login/change_password.php
index 66840ebdaabe1..560884e6a98cd 100644
--- a/login/change_password.php
+++ b/login/change_password.php
@@ -56,7 +56,7 @@
 $strparticipants = get_string('participants');
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 // require proper login; guest user can not change password
@@ -78,7 +78,7 @@
 
 // do not allow "Logged in as" users to change any passwords
 if (\core\session\manager::is_loggedinas()) {
-    print_error('cannotcallscript');
+    throw new \moodle_exception('cannotcallscript');
 }
 
 if (is_mnet_remote_user($USER)) {
@@ -86,14 +86,14 @@
     if ($idprovider = $DB->get_record('mnet_host', array('id'=>$USER->mnethostid))) {
         $message .= get_string('userchangepasswordlink', 'mnet', $idprovider);
     }
-    print_error('userchangepasswordlink', 'mnet', '', $message);
+    throw new \moodle_exception('userchangepasswordlink', 'mnet', '', $message);
 }
 
 // load the appropriate auth plugin
 $userauth = get_auth_plugin($USER->auth);
 
 if (!$userauth->can_change_password()) {
-    print_error('nopasswordchange', 'auth');
+    throw new \moodle_exception('nopasswordchange', 'auth');
 }
 
 if ($changeurl = $userauth->change_password_url()) {
@@ -112,7 +112,7 @@
 } else if ($data = $mform->get_data()) {
 
     if (!$userauth->user_update_password($USER, $data->newpassword1)) {
-        print_error('errorpasswordupdate', 'auth');
+        throw new \moodle_exception('errorpasswordupdate', 'auth');
     }
 
     user_add_password_history($USER->id, $data->newpassword1);
diff --git a/login/confirm.php b/login/confirm.php
index 4e6b9f614859c..6f4d76e3f36de 100644
--- a/login/confirm.php
+++ b/login/confirm.php
@@ -72,7 +72,7 @@
         // The user has confirmed successfully, let's log them in
 
         if (!$user = get_complete_user_data('username', $username)) {
-            print_error('cannotfinduser', '', '', s($username));
+            throw new \moodle_exception('cannotfinduser', '', '', s($username));
         }
 
         if (!$user->suspended) {
@@ -101,10 +101,10 @@
         echo $OUTPUT->footer();
         exit;
     } else {
-        print_error('invalidconfirmdata');
+        throw new \moodle_exception('invalidconfirmdata');
     }
 } else {
-    print_error("errorwhenconfirming");
+    throw new \moodle_exception("errorwhenconfirming");
 }
 
 redirect("$CFG->wwwroot/");
diff --git a/login/lib.php b/login/lib.php
index de72d7cb612a3..e30e178369e5e 100644
--- a/login/lib.php
+++ b/login/lib.php
@@ -85,7 +85,7 @@ function core_login_process_password_reset($username, $email) {
     global $CFG, $DB;
 
     if (empty($username) && empty($email)) {
-        print_error('cannotmailconfirm');
+        throw new \moodle_exception('cannotmailconfirm');
     }
 
     // Next find the user account in the database which the requesting user claims to own.
@@ -135,7 +135,7 @@ function core_login_process_password_reset($username, $email) {
             if (send_password_change_info($user)) {
                 $pwresetstatus = PWRESET_STATUS_OTHEREMAILSENT;
             } else {
-                print_error('cannotmailconfirm');
+                throw new \moodle_exception('cannotmailconfirm');
             }
         } else {
             // The account the requesting user claims to be is entitled to change their password.
@@ -170,7 +170,7 @@ function core_login_process_password_reset($username, $email) {
                 if ($sendresult) {
                     $pwresetstatus = PWRESET_STATUS_TOKENSENT;
                 } else {
-                    print_error('cannotmailconfirm');
+                    throw new \moodle_exception('cannotmailconfirm');
                 }
             }
         }
@@ -253,13 +253,13 @@ function core_login_process_password_set($token) {
     if ($user->auth === 'nologin' or !is_enabled_auth($user->auth)) {
         // Bad luck - user is not able to login, do not let them set password.
         echo $OUTPUT->header();
-        print_error('forgotteninvalidurl');
+        throw new \moodle_exception('forgotteninvalidurl');
         die; // Never reached.
     }
 
     // Check this isn't guest user.
     if (isguestuser($user)) {
-        print_error('cannotresetguestpwd');
+        throw new \moodle_exception('cannotresetguestpwd');
     }
 
     // Token is correct, and unexpired.
@@ -284,7 +284,7 @@ function core_login_process_password_set($token) {
         $DB->delete_records('user_password_resets', array('id' => $user->tokenid));
         $userauth = get_auth_plugin($user->auth);
         if (!$userauth->user_update_password($user, $data->password)) {
-            print_error('errorpasswordupdate', 'auth');
+            throw new \moodle_exception('errorpasswordupdate', 'auth');
         }
         user_add_password_history($user->id, $data->password);
         if (!empty($CFG->passwordchangelogout)) {
diff --git a/login/signup.php b/login/signup.php
index d46f4531efd77..f104bfe9e3260 100644
--- a/login/signup.php
+++ b/login/signup.php
@@ -30,7 +30,7 @@
 require_once('lib.php');
 
 if (!$authplugin = signup_is_enabled()) {
-    print_error('notlocalisederrormessage', 'error', '', 'Sorry, you may not use this page.');
+    throw new \moodle_exception('notlocalisederrormessage', 'error', '', 'Sorry, you may not use this page.');
 }
 
 $PAGE->set_url('/login/signup.php');
diff --git a/login/unlock_account.php b/login/unlock_account.php
index 087729a3de9fa..d5f2f91bcdaa6 100644
--- a/login/unlock_account.php
+++ b/login/unlock_account.php
@@ -37,7 +37,7 @@
 // Do not disclose details about existence or status of user accounts here.
 
 if (!$user = $DB->get_record('user', array('id'=>$userid, 'deleted'=>0, 'suspended'=>0))) {
-    print_error('lockouterrorunlock', 'admin', get_login_url());
+    throw new \moodle_exception('lockouterrorunlock', 'admin', get_login_url());
 }
 
 $usersecret = get_user_preferences('login_lockout_secret', false, $user);
@@ -51,4 +51,4 @@
     }
 }
 
-print_error('lockouterrorunlock', 'admin', get_login_url());
+throw new \moodle_exception('lockouterrorunlock', 'admin', get_login_url());
diff --git a/message/classes/api.php b/message/classes/api.php
index de89146fe9c94..7db178df53e0e 100644
--- a/message/classes/api.php
+++ b/message/classes/api.php
@@ -1911,7 +1911,7 @@ public static function get_processed_processor_object(\stdClass $processor) {
                 }
                 $processor->available = 1;
             } else {
-                print_error('errorcallingprocessor', 'message');
+                throw new \moodle_exception('errorcallingprocessor', 'message');
             }
         } else {
             $processor->available = 0;
diff --git a/message/edit.php b/message/edit.php
index f511b06a4e11a..7882f3493f376 100644
--- a/message/edit.php
+++ b/message/edit.php
@@ -41,11 +41,11 @@
 require_login();
 
 if (isguestuser()) {
-    print_error('guestnoeditmessage', 'message');
+    throw new \moodle_exception('guestnoeditmessage', 'message');
 }
 
 if (!$user = $DB->get_record('user', array('id' => $userid))) {
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 $systemcontext   = context_system::instance();
@@ -64,11 +64,11 @@
     require_capability('moodle/user:editmessageprofile', $personalcontext);
     // no editing of guest user account
     if (isguestuser($user->id)) {
-        print_error('guestnoeditmessageother', 'message');
+        throw new \moodle_exception('guestnoeditmessageother', 'message');
     }
     // no editing of admins by non admins!
     if (is_siteadmin($user) and !is_siteadmin($USER)) {
-        print_error('useradmineditadmin');
+        throw new \moodle_exception('useradmineditadmin');
     }
     $PAGE->navbar->includesettingsbase = true;
     $PAGE->navigation->extend_for_user($user);
diff --git a/message/index.php b/message/index.php
index 8e86ad7fd9638..5d9262e81f155 100644
--- a/message/index.php
+++ b/message/index.php
@@ -31,7 +31,7 @@
 }
 
 if (empty($CFG->messaging)) {
-    print_error('disabled', 'message');
+    throw new \moodle_exception('disabled', 'message');
 }
 
 // The id of the user we want to view messages from.
diff --git a/message/notificationpreferences.php b/message/notificationpreferences.php
index 9a6ac52563fab..65d10941a3476 100644
--- a/message/notificationpreferences.php
+++ b/message/notificationpreferences.php
@@ -35,7 +35,7 @@
 require_login();
 
 if (isguestuser()) {
-    print_error('guestnoeditmessage', 'message');
+    throw new \moodle_exception('guestnoeditmessage', 'message');
 }
 
 $user = $DB->get_record('user', array('id' => $userid), '*', MUST_EXIST);
@@ -55,11 +55,11 @@
     require_capability('moodle/user:editmessageprofile', $personalcontext);
     // No editing of guest user account.
     if (isguestuser($user->id)) {
-        print_error('guestnoeditmessageother', 'message');
+        throw new \moodle_exception('guestnoeditmessageother', 'message');
     }
     // No editing of admins by non admins!
     if (is_siteadmin($user) and !is_siteadmin($USER)) {
-        print_error('useradmineditadmin');
+        throw new \moodle_exception('useradmineditadmin');
     }
     $PAGE->navbar->includesettingsbase = true;
     $PAGE->navigation->extend_for_user($user);
diff --git a/message/output/popup/notifications.php b/message/output/popup/notifications.php
index a33ffe62937f8..1a2988e140df5 100644
--- a/message/output/popup/notifications.php
+++ b/message/output/popup/notifications.php
@@ -37,11 +37,11 @@
 require_login();
 
 if (isguestuser()) {
-    print_error('guestnoeditmessage', 'message');
+    throw new \moodle_exception('guestnoeditmessage', 'message');
 }
 
 if (!$user = $DB->get_record('user', ['id' => $userid])) {
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 $personalcontext = context_user::instance($user->id);
diff --git a/mnet/lib.php b/mnet/lib.php
index 2bfcc713a3c78..49e427979c5a1 100644
--- a/mnet/lib.php
+++ b/mnet/lib.php
@@ -79,7 +79,7 @@ function mnet_get_public_key($uri, $application=null) {
                 curl_setopt($ch, CURLOPT_PROXYTYPE, CURLPROXY_SOCKS5);
             } else {
                 curl_close($ch);
-                print_error( 'socksnotsupported','mnet' );
+                throw new \moodle_exception( 'socksnotsupported', 'mnet');
             }
         }
 
diff --git a/mnet/publickey.php b/mnet/publickey.php
index abdfde5cfdd9f..4a4e3c406928a 100644
--- a/mnet/publickey.php
+++ b/mnet/publickey.php
@@ -12,7 +12,7 @@
 require_once $CFG->dirroot.'/mnet/lib.php';
 
 if ($CFG->mnet_dispatcher_mode === 'off') {
-    print_error('mnetdisabled', 'mnet');
+    throw new \moodle_exception('mnetdisabled', 'mnet');
 }
 
 header("Content-type: text/plain; charset=utf-8");
diff --git a/mnet/service/enrol/course.php b/mnet/service/enrol/course.php
index 411c3226c9fda..4334fe68762ac 100644
--- a/mnet/service/enrol/course.php
+++ b/mnet/service/enrol/course.php
@@ -49,7 +49,7 @@
 $hosts = $service->get_remote_publishers();
 
 if (empty($hosts[$hostid])) {
-    print_error('wearenotsubscribedtothishost', 'mnetservice_enrol');
+    throw new \moodle_exception('wearenotsubscribedtothishost', 'mnetservice_enrol');
 }
 $host   = $hosts[$hostid];
 $course = $DB->get_record('mnetservice_enrol_courses', array('id'=>$courseid, 'hostid'=>$host->id), '*', MUST_EXIST);
diff --git a/mnet/service/enrol/host.php b/mnet/service/enrol/host.php
index 281a2cf65efe9..c5bae9f399378 100644
--- a/mnet/service/enrol/host.php
+++ b/mnet/service/enrol/host.php
@@ -49,7 +49,7 @@
 $hosts = $service->get_remote_publishers();
 
 if (empty($hosts[$hostid])) {
-    print_error('wearenotsubscribedtothishost', 'mnetservice_enrol');
+    throw new \moodle_exception('wearenotsubscribedtothishost', 'mnetservice_enrol');
 }
 $host = $hosts[$hostid];
 
@@ -59,7 +59,7 @@
 }
 $courses = $service->get_remote_courses($host->id, $usecache);
 if (is_string($courses)) {
-    print_error('fetchingcourses', 'mnetservice_enrol', '', null, $service->format_error_message($courses));
+    throw new \moodle_exception('fetchingcourses', 'mnetservice_enrol', '', null, $service->format_error_message($courses));
 }
 
 echo $OUTPUT->header();
diff --git a/mnet/service/enrol/locallib.php b/mnet/service/enrol/locallib.php
index 8f4e527a42d69..e1d3089f3c2e8 100644
--- a/mnet/service/enrol/locallib.php
+++ b/mnet/service/enrol/locallib.php
@@ -437,7 +437,7 @@ public function req_unenrol_user(stdclass $user, stdclass $remotecourse) {
     }
 
     /**
-     * Prepares error messages returned by our XML-RPC requests to be send as debug info to {@link print_error()}
+     * Prepares error messages returned by our XML-RPC requests to be send as debug info to {@see \moodle_exception()}
      *
      * MNet client-side methods in this class return request error as serialized array.
      *
diff --git a/mnet/xmlrpc/server.php b/mnet/xmlrpc/server.php
index c292e3287b268..7d702d9bb7302 100644
--- a/mnet/xmlrpc/server.php
+++ b/mnet/xmlrpc/server.php
@@ -27,7 +27,7 @@
 
 
 if ($CFG->mnet_dispatcher_mode === 'off') {
-    print_error('mnetdisabled', 'mnet');
+    throw new \moodle_exception('mnetdisabled', 'mnet');
 }
 
 // Content type for output is not html:
diff --git a/mod/assign/feedback/editpdf/ajax.php b/mod/assign/feedback/editpdf/ajax.php
index a0eda7c35b37e..624033302f347 100644
--- a/mod/assign/feedback/editpdf/ajax.php
+++ b/mod/assign/feedback/editpdf/ajax.php
@@ -48,7 +48,7 @@
 require_login($assignment->get_course(), false, $cm);
 
 if (!$assignment->can_view_submission($userid)) {
-    print_error('nopermission');
+    throw new \moodle_exception('nopermission');
 }
 
 if ($action === 'pollconversions') {
diff --git a/mod/assign/feedback/editpdf/classes/document_services.php b/mod/assign/feedback/editpdf/classes/document_services.php
index f417141596ab6..d14462b79eba1 100644
--- a/mod/assign/feedback/editpdf/classes/document_services.php
+++ b/mod/assign/feedback/editpdf/classes/document_services.php
@@ -166,7 +166,7 @@ protected static function list_compatible_submission_files_for_attempt($assignme
 
         // Capability checks.
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         $files = array();
@@ -278,7 +278,7 @@ public static function get_combined_document_for_attempt($assignment, $userid, $
 
         // Capability checks.
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermissiontoaccesspage', 'error');
         }
 
         $grade = $assignment->get_user_grade($userid, true, $attemptnumber);
@@ -363,7 +363,7 @@ public static function page_number_for_attempt($assignment, $userid, $attemptnum
         $assignment = self::get_assignment_from_param($assignment);
 
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         // When in readonly we can return the number of images in the DB because they should already exist,
@@ -400,7 +400,7 @@ protected static function generate_page_images_for_attempt($assignment, $userid,
         $assignment = self::get_assignment_from_param($assignment);
 
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         // Need to generate the page images - first get a combined pdf.
@@ -408,7 +408,7 @@ protected static function generate_page_images_for_attempt($assignment, $userid,
 
         $status = $document->get_status();
         if ($status === combined_document::STATUS_FAILED) {
-            print_error('Could not generate combined pdf.');
+            throw new \moodle_exception('Could not generate combined pdf.');
         } else if ($status === combined_document::STATUS_PENDING_INPUT) {
             // The conversion is still in progress.
             return [];
@@ -499,7 +499,7 @@ public static function get_page_images_for_attempt($assignment, $userid, $attemp
         $assignment = self::get_assignment_from_param($assignment);
 
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         if ($assignment->get_instance()->teamsubmission) {
@@ -645,10 +645,10 @@ public static function generate_feedback_document($assignment, $userid, $attempt
         $assignment = self::get_assignment_from_param($assignment);
 
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
         if (!$assignment->can_grade()) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         // Need to generate the page images - first get a combined pdf.
@@ -656,7 +656,7 @@ public static function generate_feedback_document($assignment, $userid, $attempt
 
         $status = $document->get_status();
         if ($status === combined_document::STATUS_FAILED) {
-            print_error('Could not generate combined pdf.');
+            throw new \moodle_exception('Could not generate combined pdf.');
         } else if ($status === combined_document::STATUS_PENDING_INPUT) {
             // The conversion is still in progress.
             return false;
@@ -814,7 +814,7 @@ public static function get_feedback_document($assignment, $userid, $attemptnumbe
         $assignment = self::get_assignment_from_param($assignment);
 
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         $grade = $assignment->get_user_grade($userid, true, $attemptnumber);
@@ -850,10 +850,10 @@ public static function delete_feedback_document($assignment, $userid, $attemptnu
         $assignment = self::get_assignment_from_param($assignment);
 
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
         if (!$assignment->can_grade()) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         $grade = $assignment->get_user_grade($userid, true, $attemptnumber);
@@ -944,7 +944,7 @@ public static function rotate_page($assignment, $userid, $attemptnumber, $index,
         $grade = $assignment->get_user_grade($userid, true, $attemptnumber);
         // Check permission.
         if (!$assignment->can_view_submission($userid)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
 
         $filearea = self::PAGE_IMAGE_FILEAREA;
diff --git a/mod/assign/feedback/file/importzipform.php b/mod/assign/feedback/file/importzipform.php
index 2e6840eb2026f..d67d3a45afa42 100644
--- a/mod/assign/feedback/file/importzipform.php
+++ b/mod/assign/feedback/file/importzipform.php
@@ -54,7 +54,7 @@ public function definition() {
         $update = false;
 
         if (!$importer) {
-            print_error('invalidarguments');
+            throw new \moodle_exception('invalidarguments');
             return;
         }
 
diff --git a/mod/assign/feedback/offline/importgradesform.php b/mod/assign/feedback/offline/importgradesform.php
index 32652073fdaa6..19f58c966c985 100644
--- a/mod/assign/feedback/offline/importgradesform.php
+++ b/mod/assign/feedback/offline/importgradesform.php
@@ -57,7 +57,7 @@ public function definition() {
         $draftid = $params['draftid'];
 
         if (!$gradeimporter) {
-            print_error('invalidarguments');
+            throw new \moodle_exception('invalidarguments');
             return;
         }
 
@@ -77,7 +77,7 @@ public function definition() {
                                                                      'plugin'=>'offline',
                                                                      'pluginaction'=>'uploadgrades',
                                                                      'id'=>$assignment->get_course_module()->id));
-            print_error('invalidgradeimport', 'assignfeedback_offline', $thisurl);
+            throw new \moodle_exception('invalidgradeimport', 'assignfeedback_offline', $thisurl);
             return;
         }
 
diff --git a/mod/assign/feedback/offline/locallib.php b/mod/assign/feedback/offline/locallib.php
index c93246147eea9..ecba77927f538 100644
--- a/mod/assign/feedback/offline/locallib.php
+++ b/mod/assign/feedback/offline/locallib.php
@@ -119,7 +119,7 @@ public function process_import_grades($draftid, $importid, $ignoremodified, $enc
                                                                      'plugin'=>'offline',
                                                                      'pluginaction'=>'uploadgrades',
                                                                      'id' => $this->assignment->get_course_module()->id));
-            print_error('invalidgradeimport', 'assignfeedback_offline', $thisurl);
+            throw new \moodle_exception('invalidgradeimport', 'assignfeedback_offline', $thisurl);
             return;
         }
         // Does this assignment use a scale?
diff --git a/mod/assign/locallib.php b/mod/assign/locallib.php
index 7a28e308c0c7f..286b625232157 100644
--- a/mod/assign/locallib.php
+++ b/mod/assign/locallib.php
@@ -776,13 +776,13 @@ public function add_instance(stdClass $formdata, $callplugins) {
             // Call save_settings hook for submission plugins.
             foreach ($this->submissionplugins as $plugin) {
                 if (!$this->update_plugin_instance($plugin, $formdata)) {
-                    print_error($plugin->get_error());
+                    throw new \moodle_exception($plugin->get_error());
                     return false;
                 }
             }
             foreach ($this->feedbackplugins as $plugin) {
                 if (!$this->update_plugin_instance($plugin, $formdata)) {
-                    print_error($plugin->get_error());
+                    throw new \moodle_exception($plugin->get_error());
                     return false;
                 }
             }
@@ -836,13 +836,13 @@ public function delete_instance() {
 
         foreach ($this->submissionplugins as $plugin) {
             if (!$plugin->delete_instance()) {
-                print_error($plugin->get_error());
+                throw new \moodle_exception($plugin->get_error());
                 $result = false;
             }
         }
         foreach ($this->feedbackplugins as $plugin) {
             if (!$plugin->delete_instance()) {
-                print_error($plugin->get_error());
+                throw new \moodle_exception($plugin->get_error());
                 $result = false;
             }
         }
@@ -1300,7 +1300,7 @@ protected function update_plugin_instance(assign_plugin $plugin, stdClass $formd
             if (!empty($formdata->$enabledname)) {
                 $plugin->enable();
                 if (!$plugin->save_settings($formdata)) {
-                    print_error($plugin->get_error());
+                    throw new \moodle_exception($plugin->get_error());
                     return false;
                 }
             } else {
@@ -1542,13 +1542,13 @@ public function update_instance($formdata) {
         // Call save_settings hook for submission plugins.
         foreach ($this->submissionplugins as $plugin) {
             if (!$this->update_plugin_instance($plugin, $formdata)) {
-                print_error($plugin->get_error());
+                throw new \moodle_exception($plugin->get_error());
                 return false;
             }
         }
         foreach ($this->feedbackplugins as $plugin) {
             if (!$this->update_plugin_instance($plugin, $formdata)) {
-                print_error($plugin->get_error());
+                throw new \moodle_exception($plugin->get_error());
                 return false;
             }
         }
@@ -3288,7 +3288,7 @@ protected function view_plugin_page() {
 
         $plugin = $this->get_plugin_by_type($pluginsubtype, $plugintype);
         if (!$plugin) {
-            print_error('invalidformdata', '');
+            throw new \moodle_exception('invalidformdata', '');
             return;
         }
 
@@ -4463,7 +4463,7 @@ protected function view_remove_submission_confirm() {
         $userid = optional_param('userid', $USER->id, PARAM_INT);
 
         if (!$this->can_edit_submission($userid, $USER->id)) {
-            print_error('nopermission');
+            throw new \moodle_exception('nopermission');
         }
         $user = core_user::get_user($userid, '*', MUST_EXIST);
 
@@ -4930,7 +4930,7 @@ protected function view_edit_submission_page($mform, $notices) {
 
         if ($userid == $USER->id) {
             if (!$this->can_edit_submission($userid, $USER->id)) {
-                print_error('nopermission');
+                throw new \moodle_exception('nopermission');
             }
             // User is editing their own submission.
             require_capability('mod/assign:submit', $this->context);
@@ -4938,7 +4938,7 @@ protected function view_edit_submission_page($mform, $notices) {
         } else {
             // User is editing another user's submission.
             if (!$this->can_edit_submission($userid, $USER->id)) {
-                print_error('nopermission');
+                throw new \moodle_exception('nopermission');
             }
 
             $name = $this->fullname($user);
@@ -5120,7 +5120,7 @@ protected function view_plugin_grading_batch_operation($mform) {
                 return;
             }
         }
-        print_error('invalidformdata', '');
+        throw new \moodle_exception('invalidformdata', '');
     }
 
     /**
@@ -6818,7 +6818,7 @@ public function submit_for_grading($data, $notices) {
             require_capability('mod/assign:submit', $this->context);
         } else {
             if (!$this->can_edit_submission($userid, $USER->id)) {
-                print_error('nopermission');
+                throw new \moodle_exception('nopermission');
             }
         }
 
@@ -7664,7 +7664,7 @@ public function save_submission(stdClass $data, & $notices) {
         } else {
             $user = $DB->get_record('user', array('id'=>$userid), '*', MUST_EXIST);
             if (!$this->can_edit_submission($userid, $USER->id)) {
-                print_error('nopermission');
+                throw new \moodle_exception('nopermission');
             }
         }
         $instance = $this->get_instance();
@@ -7700,7 +7700,7 @@ public function save_submission(stdClass $data, & $notices) {
 
         // Get the flags to check if it is locked.
         if ($flags && $flags->locked) {
-            print_error('submissionslocked', 'assign');
+            throw new \moodle_exception('submissionslocked', 'assign');
             return true;
         }
 
@@ -8685,7 +8685,7 @@ protected function apply_grade_to_user($formdata, $userid, $attemptnumber) {
                 if ($gradingmodified) {
                     if (!$plugin->save($grade, $formdata)) {
                         $result = false;
-                        print_error($plugin->get_error());
+                        throw new \moodle_exception($plugin->get_error());
                     }
                     // If $feedbackmodified is true, keep it true.
                     $feedbackmodified = $feedbackmodified || $gradingmodified;
diff --git a/mod/assign/override_form.php b/mod/assign/override_form.php
index 2533f8338101e..cce7bf41a62f9 100644
--- a/mod/assign/override_form.php
+++ b/mod/assign/override_form.php
@@ -122,7 +122,7 @@ protected function definition() {
                 if (empty($groups)) {
                     // Generate an error.
                     $link = new moodle_url('/mod/assign/overrides.php', array('cmid' => $cm->id));
-                    print_error('groupsnone', 'assign', $link);
+                    throw new \moodle_exception('groupsnone', 'assign', $link);
                 }
 
                 $groupchoices = array();
@@ -182,7 +182,7 @@ protected function definition() {
                 if (empty($users)) {
                     // Generate an error.
                     $link = new moodle_url('/mod/assign/overrides.php', array('cmid' => $cm->id));
-                    print_error('usersnone', 'assign', $link);
+                    throw new \moodle_exception('usersnone', 'assign', $link);
                 }
 
                 $userchoices = array();
diff --git a/mod/assign/overridedelete.php b/mod/assign/overridedelete.php
index 6121308adc8ef..fb8a07c64f212 100644
--- a/mod/assign/overridedelete.php
+++ b/mod/assign/overridedelete.php
@@ -32,7 +32,7 @@
 $confirm = optional_param('confirm', false, PARAM_BOOL);
 
 if (! $override = $DB->get_record('assign_overrides', array('id' => $overrideid))) {
-    print_error('invalidoverrideid', 'assign');
+    throw new \moodle_exception('invalidoverrideid', 'assign');
 }
 
 list($course, $cm) = get_course_and_cm_from_instance($override->assignid, 'assign');
@@ -46,11 +46,11 @@
 
 if ($override->groupid) {
     if (!groups_group_visible($override->groupid, $course, $cm)) {
-        print_error('invalidoverrideid', 'assign');
+        throw new \moodle_exception('invalidoverrideid', 'assign');
     }
 } else {
     if (!groups_user_groups_visible($course, $override->userid, $cm)) {
-        print_error('invalidoverrideid', 'assign');
+        throw new \moodle_exception('invalidoverrideid', 'assign');
     }
 }
 
diff --git a/mod/assign/overrideedit.php b/mod/assign/overrideedit.php
index 1702bb05879c2..76fb11b2f827a 100644
--- a/mod/assign/overrideedit.php
+++ b/mod/assign/overrideedit.php
@@ -42,7 +42,7 @@
 if ($overrideid) {
 
     if (! $override = $DB->get_record('assign_overrides', array('id' => $overrideid))) {
-        print_error('invalidoverrideid', 'assign');
+        throw new \moodle_exception('invalidoverrideid', 'assign');
     }
 
     list($course, $cm) = get_course_and_cm_from_instance($override->assignid, 'assign');
@@ -51,7 +51,7 @@
     list($course, $cm) = get_course_and_cm_from_cmid($cmid, 'assign');
 
 } else {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $url = new moodle_url('/mod/assign/overrideedit.php');
@@ -83,11 +83,11 @@
 
     if ($override->groupid) {
         if (!groups_group_visible($override->groupid, $course, $cm)) {
-            print_error('invalidoverrideid', 'assign');
+            throw new \moodle_exception('invalidoverrideid', 'assign');
         }
     } else {
         if (!groups_user_groups_visible($course, $override->userid, $cm)) {
-            print_error('invalidoverrideid', 'assign');
+            throw new \moodle_exception('invalidoverrideid', 'assign');
         }
     }
 } else {
diff --git a/mod/assignment/mod_form.php b/mod/assignment/mod_form.php
index f554e810771d6..f2985f47dd63e 100644
--- a/mod/assignment/mod_form.php
+++ b/mod/assignment/mod_form.php
@@ -41,7 +41,7 @@ class mod_assignment_mod_form extends moodleform_mod {
      * @return void
      */
     public function definition() {
-        print_error('assignmentdisabled', 'assignment');
+        throw new \moodle_exception('assignmentdisabled', 'assignment');
     }
 
 
diff --git a/mod/assignment/view.php b/mod/assignment/view.php
index 1e5a9177da1a9..da25b1d27db66 100644
--- a/mod/assignment/view.php
+++ b/mod/assignment/view.php
@@ -5,4 +5,4 @@
 require_login();
 $PAGE->set_context(context_system::instance());
 
-print_error('assignmentneedsupgrade', 'assignment', '');
+throw new \moodle_exception('assignmentneedsupgrade', 'assignment', '');
diff --git a/mod/book/tool/exportimscp/locallib.php b/mod/book/tool/exportimscp/locallib.php
index 0c1a39bc9ad92..6508dbc890fe1 100644
--- a/mod/book/tool/exportimscp/locallib.php
+++ b/mod/book/tool/exportimscp/locallib.php
@@ -47,7 +47,7 @@ function booktool_exportimscp_build_package($book, $context) {
 
     // fix structure and test if chapters present
     if (!book_preload_chapters($book)) {
-        print_error('nochapters', 'booktool_exportimscp');
+        throw new \moodle_exception('nochapters', 'booktool_exportimscp');
     }
 
     // prepare temp area with package contents
diff --git a/mod/chat/gui_ajax/index.php b/mod/chat/gui_ajax/index.php
index eee084a801071..a9b60c5c22d03 100644
--- a/mod/chat/gui_ajax/index.php
+++ b/mod/chat/gui_ajax/index.php
@@ -41,7 +41,7 @@
 if ($groupmode = groups_get_activity_groupmode($cm)) {   // Groups are being used.
     if ($groupid = groups_get_activity_group($cm)) {
         if (!$group = groups_get_group($groupid)) {
-            print_error('invalidgroupid');
+            throw new \moodle_exception('invalidgroupid');
         }
         $groupname = ': '.$group->name;
     } else {
@@ -58,7 +58,7 @@
 
 // Log into the chat room.
 if (!$chatsid = chat_login_user($chat->id, 'ajax', $groupid, $course)) {
-    print_error('cantlogin', 'chat');
+    throw new \moodle_exception('cantlogin', 'chat');
 }
 $courseshortname = format_string($course->shortname, true, array('context' => context_course::instance($course->id)));
 $module = array(
diff --git a/mod/chat/gui_basic/index.php b/mod/chat/gui_basic/index.php
index 9001f7de7df9e..6468b01405444 100644
--- a/mod/chat/gui_basic/index.php
+++ b/mod/chat/gui_basic/index.php
@@ -43,15 +43,15 @@
 $PAGE->set_url($url);
 
 if (!$chat = $DB->get_record('chat', array('id' => $id))) {
-    print_error('invalidid', 'chat');
+    throw new \moodle_exception('invalidid', 'chat');
 }
 
 if (!$course = $DB->get_record('course', array('id' => $chat->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if (!$cm = get_coursemodule_from_instance('chat', $chat->id, $course->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $context = context_module::instance($cm->id);
@@ -64,7 +64,7 @@
 if ($groupmode = groups_get_activity_groupmode($cm)) { // Groups are being used.
     if ($groupid = groups_get_activity_group($cm)) {
         if (!$group = groups_get_group($groupid)) {
-            print_error('invalidgroupid');
+            throw new \moodle_exception('invalidgroupid');
         }
         $groupname = ': '.$group->name;
     } else {
@@ -79,11 +79,11 @@
 $strchats = get_string('modulenameplural', 'chat');
 $stridle  = get_string('idle', 'chat');
 if (!$chatsid = chat_login_user($chat->id, 'basic', $groupid, $course)) {
-    print_error('cantlogin', 'chat');
+    throw new \moodle_exception('cantlogin', 'chat');
 }
 
 if (!$chatusers = chat_get_users($chat->id, $groupid, $cm->groupingid)) {
-    print_error('errornousers', 'chat');
+    throw new \moodle_exception('errornousers', 'chat');
 }
 
 $DB->set_field('chat_users', 'lastping', time(), array('sid' => $chatsid));
diff --git a/mod/chat/gui_header_js/chatinput.php b/mod/chat/gui_header_js/chatinput.php
index 445d704bfe874..0ba15b3952dab 100644
--- a/mod/chat/gui_header_js/chatinput.php
+++ b/mod/chat/gui_header_js/chatinput.php
@@ -23,18 +23,18 @@
 $chatid   = required_param('chat_id', PARAM_INT);
 
 if (!$chatuser = $DB->get_record('chat_users', array('sid' => $chatsid))) {
-    print_error('notlogged', 'chat');
+    throw new \moodle_exception('notlogged', 'chat');
 }
 if (!$chat = $DB->get_record('chat', array('id' => $chatid))) {
-    print_error('invalidid', 'chat');
+    throw new \moodle_exception('invalidid', 'chat');
 }
 
 if (!$course = $DB->get_record('course', array('id' => $chat->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if (!$cm = get_coursemodule_from_instance('chat', $chat->id, $course->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $PAGE->set_url('/mod/chat/gui_header_js/chatinput.php', array('chat_sid' => $chatsid, 'chat_id' => $chatid));
diff --git a/mod/chat/gui_header_js/index.php b/mod/chat/gui_header_js/index.php
index 6fba74e6d308b..4135cf9441e80 100644
--- a/mod/chat/gui_header_js/index.php
+++ b/mod/chat/gui_header_js/index.php
@@ -27,15 +27,15 @@
 $PAGE->set_url($url);
 
 if (!$chat = $DB->get_record('chat', array('id' => $id))) {
-    print_error('invalidid', 'chat');
+    throw new \moodle_exception('invalidid', 'chat');
 }
 
 if (!$course = $DB->get_record('course', array('id' => $chat->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if (!$cm = get_coursemodule_from_instance('chat', $chat->id, $course->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $context = context_module::instance($cm->id);
@@ -48,7 +48,7 @@
 if ($groupmode = groups_get_activity_groupmode($cm)) {   // Groups are being used.
     if ($groupid = groups_get_activity_group($cm)) {
         if (!$group = groups_get_group($groupid)) {
-            print_error('invalidgroupid');
+            throw new \moodle_exception('invalidgroupid');
         }
         $groupname = ': '.$group->name;
     } else {
@@ -62,7 +62,7 @@
 $strchat = get_string('modulename', 'chat'); // Must be before current_language() in chat_login_user() to force course language!
 
 if (!$chatsid = chat_login_user($chat->id, 'header_js', $groupid, $course)) {
-    print_error('cantlogin', 'chat');
+    throw new \moodle_exception('cantlogin', 'chat');
 }
 
 $params = "chat_id=$id&chat_sid={$chatsid}";
diff --git a/mod/chat/gui_header_js/insert.php b/mod/chat/gui_header_js/insert.php
index e86690adf98e0..44946a3ed9dfb 100644
--- a/mod/chat/gui_header_js/insert.php
+++ b/mod/chat/gui_header_js/insert.php
@@ -23,25 +23,25 @@
 $PAGE->set_url('/mod/chat/gui_header_js/insert.php', array('chat_sid' => $chatsid, 'chat_message' => $chatmessage));
 
 if (!$chatuser = $DB->get_record('chat_users', array('sid' => $chatsid))) {
-    print_error('notlogged', 'chat');
+    throw new \moodle_exception('notlogged', 'chat');
 }
 
 if (!$chat = $DB->get_record('chat', array('id' => $chatuser->chatid))) {
-    print_error('nochat', 'chat');
+    throw new \moodle_exception('nochat', 'chat');
 }
 
 if (!$course = $DB->get_record('course', array('id' => $chat->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if (!$cm = get_coursemodule_from_instance('chat', $chat->id, $course->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 require_login($course, false, $cm);
 
 if (isguestuser()) {
-    print_error('noguests');
+    throw new \moodle_exception('noguests');
 }
 
 \core\session\manager::write_close();
diff --git a/mod/chat/gui_header_js/jsupdate.php b/mod/chat/gui_header_js/jsupdate.php
index 29e42ef601b94..c26cf0f9b056f 100644
--- a/mod/chat/gui_header_js/jsupdate.php
+++ b/mod/chat/gui_header_js/jsupdate.php
@@ -34,18 +34,18 @@
 
 
 if (!$chatuser = $DB->get_record('chat_users', array('sid' => $chatsid))) {
-    print_error('notlogged', 'chat');
+    throw new \moodle_exception('notlogged', 'chat');
 }
 
 // Get the minimal course.
 if (!$course = $DB->get_record('course', array('id' => $chatuser->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 // Get the user theme and enough info to be used in chat_format_message() which passes it along to.
 // No optimisation here, it would break again in future!
 if (!$user = $DB->get_record('user', array('id' => $chatuser->userid, 'deleted' => 0, 'suspended' => 0))) {
-    print_error('invaliduser');
+    throw new \moodle_exception('invaliduser');
 }
 \core\session\manager::set_user($user);
 
diff --git a/mod/chat/gui_header_js/jsupdated.php b/mod/chat/gui_header_js/jsupdated.php
index 68426784ac101..cf5f0e5ee4340 100644
--- a/mod/chat/gui_header_js/jsupdated.php
+++ b/mod/chat/gui_header_js/jsupdated.php
@@ -58,19 +58,19 @@
 $PAGE->set_url($url);
 
 if (!$chatuser = $DB->get_record('chat_users', array('sid' => $chatsid))) {
-    print_error('notlogged', 'chat');
+    throw new \moodle_exception('notlogged', 'chat');
 }
 
 // Get the minimal course.
 if (!$course = $DB->get_record('course', array('id' => $chatuser->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 // Get the user theme and enough info to be used in chat_format_message() which passes it along to
 // chat_format_message_manually() -- and only id and timezone are used.
 // No optimisation here, it would break again in future!
 if (!$user = $DB->get_record('user', array('id' => $chatuser->userid, 'deleted' => 0, 'suspended' => 0))) {
-    print_error('invaliduser');
+    throw new \moodle_exception('invaliduser');
 }
 \core\session\manager::set_user($user);
 
diff --git a/mod/chat/gui_header_js/users.php b/mod/chat/gui_header_js/users.php
index 331220754c171..6d4d282b1feb9 100644
--- a/mod/chat/gui_header_js/users.php
+++ b/mod/chat/gui_header_js/users.php
@@ -26,18 +26,18 @@
 $PAGE->set_popup_notification_allowed(false);
 
 if (!$chatuser = $DB->get_record('chat_users', array('sid' => $chatsid))) {
-    print_error('notlogged', 'chat');
+    throw new \moodle_exception('notlogged', 'chat');
 }
 
 // Get the minimal course.
 if (!$course = $DB->get_record('course', array('id' => $chatuser->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 // Get the user theme and enough info to be used in chat_format_message() which passes it along to.
 // No optimisation here, it would break again in future!
 if (!$user = $DB->get_record('user', array('id' => $chatuser->userid, 'deleted' => 0, 'suspended' => 0))) {
-    print_error('invaliduser');
+    throw new \moodle_exception('invaliduser');
 }
 \core\session\manager::set_user($user);
 
@@ -49,7 +49,7 @@
 $courseid = $chatuser->course;
 
 if (!$cm = get_coursemodule_from_instance('chat', $chatuser->chatid, $courseid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if ($beep) {
@@ -65,7 +65,7 @@
 // Get list of users.
 
 if (!$chatusers = chat_get_users($chatuser->chatid, $chatuser->groupid, $cm->groupingid)) {
-    print_error('errornousers', 'chat');
+    throw new \moodle_exception('errornousers', 'chat');
 }
 
 $uidles = Array();
diff --git a/mod/chat/gui_sockets/chatinput.php b/mod/chat/gui_sockets/chatinput.php
index 799731e2f520d..071e300be94f8 100644
--- a/mod/chat/gui_sockets/chatinput.php
+++ b/mod/chat/gui_sockets/chatinput.php
@@ -25,7 +25,7 @@
 $PAGE->set_popup_notification_allowed(false);
 
 if (!$chatuser = $DB->get_record('chat_users', array('sid' => $chatsid))) {
-    print_error('notlogged', 'chat');
+    throw new \moodle_exception('notlogged', 'chat');
 }
 
 // Get the user theme.
diff --git a/mod/chat/gui_sockets/index.php b/mod/chat/gui_sockets/index.php
index ace009d0218c6..4fc7b54be93d1 100644
--- a/mod/chat/gui_sockets/index.php
+++ b/mod/chat/gui_sockets/index.php
@@ -27,15 +27,15 @@
 $PAGE->set_url($url);
 
 if (!$chat = $DB->get_record('chat', array('id' => $id))) {
-    print_error('invalidid', 'chat');
+    throw new \moodle_exception('invalidid', 'chat');
 }
 
 if (!$course = $DB->get_record('course', array('id' => $chat->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if (!$cm = get_coursemodule_from_instance('chat', $chat->id, $course->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 require_login($course, false, $cm);
@@ -46,7 +46,7 @@
 if ($groupmode = groups_get_activity_groupmode($cm)) {   // Groups are being used.
     if ($groupid = groups_get_activity_group($cm)) {
         if (!$group = groups_get_group($groupid)) {
-            print_error('invalidgroupid');
+            throw new \moodle_exception('invalidgroupid');
         }
         $groupname = ': '.$group->name;
     } else {
@@ -60,7 +60,7 @@
 $strchat = get_string('modulename', 'chat'); // Must be before current_language() in chat_login_user() to force course language!
 
 if (!$chatsid = chat_login_user($chat->id, 'sockets', $groupid, $course)) {
-    print_error('cantlogin');
+    throw new \moodle_exception('cantlogin');
 }
 
 $params = "chat_sid=$chatsid";
diff --git a/mod/chat/index.php b/mod/chat/index.php
index 41e2514784ea0..be83bd5759580 100644
--- a/mod/chat/index.php
+++ b/mod/chat/index.php
@@ -22,7 +22,7 @@
 $PAGE->set_url('/mod/chat/index.php', array('id' => $id));
 
 if (! $course = $DB->get_record('course', array('id' => $id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_course_login($course);
diff --git a/mod/chat/report.php b/mod/chat/report.php
index 5828de9369c51..050c1446daf16 100644
--- a/mod/chat/report.php
+++ b/mod/chat/report.php
@@ -42,13 +42,13 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('chat', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 if (! $chat = $DB->get_record('chat', array('id' => $cm->instance))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 if (! $course = $DB->get_record('course', array('id' => $chat->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 $context = context_module::instance($cm->id);
diff --git a/mod/chat/view.php b/mod/chat/view.php
index 06261e994f583..1626f512de7c7 100644
--- a/mod/chat/view.php
+++ b/mod/chat/view.php
@@ -26,30 +26,30 @@
 
 if ($id) {
     if (! $cm = get_coursemodule_from_id('chat', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     if (! $course = $DB->get_record('course', array('id' => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
 
     chat_update_chat_times($cm->instance);
 
     if (! $chat = $DB->get_record('chat', array('id' => $cm->instance))) {
-        print_error('invalidid', 'chat');
+        throw new \moodle_exception('invalidid', 'chat');
     }
 
 } else {
     chat_update_chat_times($c);
 
     if (! $chat = $DB->get_record('chat', array('id' => $c))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $course = $DB->get_record('course', array('id' => $chat->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('chat', $chat->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
diff --git a/mod/choice/index.php b/mod/choice/index.php
index 0fdff7f593a03..5616a1c89fa12 100644
--- a/mod/choice/index.php
+++ b/mod/choice/index.php
@@ -8,7 +8,7 @@
     $PAGE->set_url('/mod/choice/index.php', array('id'=>$id));
 
     if (!$course = $DB->get_record('course', array('id'=>$id))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
     require_course_login($course);
diff --git a/mod/choice/lib.php b/mod/choice/lib.php
index 896f4c23c1dd4..d91cb22e9a2fa 100644
--- a/mod/choice/lib.php
+++ b/mod/choice/lib.php
@@ -330,12 +330,12 @@ function choice_user_submit_response($formanswer, $choice, $userid, $course, $cm
     $continueurl = new moodle_url('/mod/choice/view.php', array('id' => $cm->id));
 
     if (empty($formanswer)) {
-        print_error('atleastoneoption', 'choice', $continueurl);
+        throw new \moodle_exception('atleastoneoption', 'choice', $continueurl);
     }
 
     if (is_array($formanswer)) {
         if (!$choice->allowmultiple) {
-            print_error('multiplenotallowederror', 'choice', $continueurl);
+            throw new \moodle_exception('multiplenotallowederror', 'choice', $continueurl);
         }
         $formanswers = $formanswer;
     } else {
@@ -345,7 +345,7 @@ function choice_user_submit_response($formanswer, $choice, $userid, $course, $cm
     $options = $DB->get_records('choice_options', array('choiceid' => $choice->id), '', 'id');
     foreach ($formanswers as $key => $val) {
         if (!isset($options[$val])) {
-            print_error('cannotsubmit', 'choice', $continueurl);
+            throw new \moodle_exception('cannotsubmit', 'choice', $continueurl);
         }
     }
     // Start lock to prevent synchronous access to the same data
@@ -360,7 +360,7 @@ function choice_user_submit_response($formanswer, $choice, $userid, $course, $cm
         // Opening the lock.
         $choicelock = $lockfactory->get_lock($resouce, $timeout, MINSECS);
         if (!$choicelock) {
-            print_error('cannotsubmit', 'choice', $continueurl);
+            throw new \moodle_exception('cannotsubmit', 'choice', $continueurl);
         }
     }
 
@@ -476,7 +476,7 @@ function choice_user_submit_response($formanswer, $choice, $userid, $course, $cm
     } else {
         // This is a choice with limited options, and one of the options selected has just run over its limit.
         $choicelock->release();
-        print_error('choicefull', 'choice', $continueurl);
+        throw new \moodle_exception('choicefull', 'choice', $continueurl);
     }
 
     // Release lock.
diff --git a/mod/choice/report.php b/mod/choice/report.php
index 3beede9aa064c..dd9c8a1ee0e35 100644
--- a/mod/choice/report.php
+++ b/mod/choice/report.php
@@ -19,11 +19,11 @@
     $PAGE->set_url($url);
 
     if (! $cm = get_coursemodule_from_id('choice', $id)) {
-        print_error("invalidcoursemodule");
+        throw new \moodle_exception("invalidcoursemodule");
     }
 
     if (! $course = $DB->get_record("course", array("id" => $cm->course))) {
-        print_error("coursemisconf");
+        throw new \moodle_exception("coursemisconf");
     }
 
     require_login($course, false, $cm);
@@ -33,7 +33,7 @@
     require_capability('mod/choice:readresponses', $context);
 
     if (!$choice = choice_get_choice($cm->instance)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     $strchoice = get_string("modulename", "choice");
diff --git a/mod/choice/view.php b/mod/choice/view.php
index 6314ad0b9c415..9f9b8b6a711cc 100644
--- a/mod/choice/view.php
+++ b/mod/choice/view.php
@@ -17,18 +17,18 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('choice', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $cm = cm_info::create($cm);
 
 if (! $course = $DB->get_record("course", array("id" => $cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 require_course_login($course, false, $cm);
 
 if (!$choice = choice_get_choice($cm->instance)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $strchoice = get_string('modulename', 'choice');
diff --git a/mod/data/edit.php b/mod/data/edit.php
index 809a8435d951d..dbaad1e54ca25 100644
--- a/mod/data/edit.php
+++ b/mod/data/edit.php
@@ -48,26 +48,26 @@
     $url->param('id', $id);
     $PAGE->set_url($url);
     if (! $cm = get_coursemodule_from_id('data', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record('course', array('id'=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $data = $DB->get_record('data', array('id'=>$cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
 } else {
     $url->param('d', $d);
     $PAGE->set_url($url);
     if (! $data = $DB->get_record('data', array('id'=>$d))) {
-        print_error('invalidid', 'data');
+        throw new \moodle_exception('invalidid', 'data');
     }
     if (! $course = $DB->get_record('course', array('id'=>$data->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('data', $data->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
@@ -111,11 +111,11 @@
     if ($rid) {
         // User is editing an existing record
         if (!data_user_can_manage_entry($record, $data, $context)) {
-            print_error('noaccess','data');
+            throw new \moodle_exception('noaccess', 'data');
         }
     } else if (!data_user_can_add_entry($data, $currentgroup, $groupmode, $context)) {
         // User is trying to create a new record
-        print_error('noaccess','data');
+        throw new \moodle_exception('noaccess', 'data');
     }
 }
 
@@ -318,7 +318,7 @@
 
 // Print the stuff that need to come after the form fields.
 if (!$fields = $DB->get_records('data_fields', array('dataid'=>$data->id))) {
-    print_error('nofieldindatabase', 'data');
+    throw new \moodle_exception('nofieldindatabase', 'data');
 }
 foreach ($fields as $eachfield) {
     $field = data_get_field($eachfield, $data);
diff --git a/mod/data/export.php b/mod/data/export.php
index 4f891c22adf5a..449b8468135ed 100644
--- a/mod/data/export.php
+++ b/mod/data/export.php
@@ -39,15 +39,15 @@
 $PAGE->set_url($url);
 
 if (! $data = $DB->get_record('data', array('id'=>$d))) {
-    print_error('wrongdataid', 'data');
+    throw new \moodle_exception('wrongdataid', 'data');
 }
 
 if (! $cm = get_coursemodule_from_instance('data', $data->id, $data->course)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if(! $course = $DB->get_record('course', array('id'=>$cm->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 // fill in missing properties needed for updating of instance
@@ -67,7 +67,7 @@
     if (has_capability('mod/data:managetemplates', $context)) {
         redirect($CFG->wwwroot.'/mod/data/field.php?d='.$data->id);
     } else {
-        print_error('nofieldindatabase', 'data');
+        throw new \moodle_exception('nofieldindatabase', 'data');
     }
 }
 
diff --git a/mod/data/field.php b/mod/data/field.php
index eb173872ad14c..21368cc8e3def 100644
--- a/mod/data/field.php
+++ b/mod/data/field.php
@@ -69,26 +69,26 @@
     $url->param('id', $id);
     $PAGE->set_url($url);
     if (! $cm = get_coursemodule_from_id('data', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record('course', array('id'=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $data = $DB->get_record('data', array('id'=>$cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
 } else {
     $url->param('d', $d);
     $PAGE->set_url($url);
     if (! $data = $DB->get_record('data', array('id'=>$d))) {
-        print_error('invalidid', 'data');
+        throw new \moodle_exception('invalidid', 'data');
     }
     if (! $course = $DB->get_record('course', array('id'=>$data->course))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $cm = get_coursemodule_from_instance('data', $data->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
diff --git a/mod/data/field/latlong/kml.php b/mod/data/field/latlong/kml.php
index 2a68d4cb8d10e..e4f60b3e43649 100644
--- a/mod/data/field/latlong/kml.php
+++ b/mod/data/field/latlong/kml.php
@@ -34,41 +34,41 @@
 
 if ($rid) {
     if (! $record = $DB->get_record('data_records', array('id'=>$rid))) {
-        print_error('invalidrecord', 'data');
+        throw new \moodle_exception('invalidrecord', 'data');
     }
     if (! $data = $DB->get_record('data', array('id'=>$record->dataid))) {
-        print_error('invalidid', 'data');
+        throw new \moodle_exception('invalidid', 'data');
     }
     if (! $course = $DB->get_record('course', array('id'=>$data->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('data', $data->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $field = $DB->get_record('data_fields', array('id'=>$fieldid))) {
-        print_error('invalidfieldid', 'data');
+        throw new \moodle_exception('invalidfieldid', 'data');
     }
     if (! $field->type == 'latlong') { // Make sure we're looking at a latlong data type!
-        print_error('invalidfieldtype', 'data');
+        throw new \moodle_exception('invalidfieldtype', 'data');
     }
     if (! $content = $DB->get_record('data_content', array('fieldid'=>$fieldid, 'recordid'=>$rid))) {
-        print_error('nofieldcontent', 'data');
+        throw new \moodle_exception('nofieldcontent', 'data');
     }
 } else {   // We must have $d
     if (! $data = $DB->get_record('data', array('id'=>$d))) {
-        print_error('invalidid', 'data');
+        throw new \moodle_exception('invalidid', 'data');
     }
     if (! $course = $DB->get_record('course', array('id'=>$data->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('data', $data->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $field = $DB->get_record('data_fields', array('id'=>$fieldid))) {
-        print_error('invalidfieldid', 'data');
+        throw new \moodle_exception('invalidfieldid', 'data');
     }
     if (! $field->type == 'latlong') { // Make sure we're looking at a latlong data type!
-        print_error('invalidfieldtype', 'data');
+        throw new \moodle_exception('invalidfieldtype', 'data');
     }
     $record = NULL;
 }
diff --git a/mod/data/index.php b/mod/data/index.php
index 292098d94e4fb..22f57ac8c6147 100644
--- a/mod/data/index.php
+++ b/mod/data/index.php
@@ -31,7 +31,7 @@
 $PAGE->set_url('/mod/data/index.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_course_login($course);
diff --git a/mod/data/lib.php b/mod/data/lib.php
index c81348cfc39d1..469fbf20d8c6d 100644
--- a/mod/data/lib.php
+++ b/mod/data/lib.php
@@ -95,18 +95,18 @@ function __construct($field=0, $data=0, $cm=0) {   // Field or data or both, eac
         global $DB;
 
         if (empty($field) && empty($data)) {
-            print_error('missingfield', 'data');
+            throw new \moodle_exception('missingfield', 'data');
         }
 
         if (!empty($field)) {
             if (is_object($field)) {
                 $this->field = $field;  // Programmer knows what they are doing, we hope
             } else if (!$this->field = $DB->get_record('data_fields', array('id'=>$field))) {
-                print_error('invalidfieldid', 'data');
+                throw new \moodle_exception('invalidfieldid', 'data');
             }
             if (empty($data)) {
                 if (!$this->data = $DB->get_record('data', array('id'=>$this->field->dataid))) {
-                    print_error('invalidid', 'data');
+                    throw new \moodle_exception('invalidid', 'data');
                 }
             }
         }
@@ -116,10 +116,10 @@ function __construct($field=0, $data=0, $cm=0) {   // Field or data or both, eac
                 if (is_object($data)) {
                     $this->data = $data;  // Programmer knows what they are doing, we hope
                 } else if (!$this->data = $DB->get_record('data', array('id'=>$data))) {
-                    print_error('invalidid', 'data');
+                    throw new \moodle_exception('invalidid', 'data');
                 }
             } else {                      // No way to define it!
-                print_error('missingdata', 'data');
+                throw new \moodle_exception('missingdata', 'data');
             }
         }
 
@@ -2545,7 +2545,7 @@ public function get_preset_settings() {
             }
 
             if (empty($fileobj)) {
-                print_error('invalidpreset', 'data', '', $this->directory);
+                throw new \moodle_exception('invalidpreset', 'data', '', $this->directory);
             }
         }
 
@@ -2639,7 +2639,7 @@ function import($overwritesettings) {
                     continue;
                 }
                 if (array_key_exists($cid, $preservedfields)){
-                    print_error('notinjectivemap', 'data');
+                    throw new \moodle_exception('notinjectivemap', 'data');
                 }
                 else $preservedfields[$cid] = true;
             }
@@ -3076,10 +3076,10 @@ function data_import_csv($cm, $data, &$csvdata, $encoding, $fielddelimiter) {
     $readcount = $cir->load_csv_content($csvdata, $encoding, $fielddelimiter);
     $csvdata = null; // Free memory.
     if (empty($readcount)) {
-        print_error('csvfailed', 'data', "{$CFG->wwwroot}/mod/data/edit.php?d={$data->id}");
+        throw new \moodle_exception('csvfailed', 'data', "{$CFG->wwwroot}/mod/data/edit.php?d={$data->id}");
     } else {
         if (!$fieldnames = $cir->get_columns()) {
-            print_error('cannotreadtmpfile', 'error');
+            throw new \moodle_exception('cannotreadtmpfile', 'error');
         }
 
         // Check the fieldnames are valid.
@@ -3116,7 +3116,7 @@ function data_import_csv($cm, $data, &$csvdata, $encoding, $fielddelimiter) {
         }
 
         if (!empty($errorfield)) {
-            print_error('fieldnotmatched', 'data',
+            throw new \moodle_exception('fieldnotmatched', 'data',
                 "{$CFG->wwwroot}/mod/data/edit.php?d={$data->id}", $errorfield);
         }
 
@@ -3823,7 +3823,7 @@ function data_presets_export($course, $cm, $data, $tostorage=false) {
 
     // Check if all files have been generated
     if (! is_directory_a_preset($exportdir)) {
-        print_error('generateerror', 'data');
+        throw new \moodle_exception('generateerror', 'data');
     }
 
     $filenames = array(
diff --git a/mod/data/preset.php b/mod/data/preset.php
index d52ad5a485552..dcdb3a2f93d0f 100644
--- a/mod/data/preset.php
+++ b/mod/data/preset.php
@@ -74,7 +74,7 @@
 
 if ($action === 'export') {
     if (headers_sent()) {
-        print_error('headersent');
+        throw new \moodle_exception('headersent');
     }
 
     $exportfile = data_presets_export($course, $cm, $data);
@@ -147,7 +147,7 @@
             }
         }
         if (!isset($selectedpreset->shortname) || !data_user_can_delete_preset($context, $selectedpreset)) {
-            print_error('invalidrequest');
+            throw new \moodle_exception('invalidrequest');
         }
 
         data_delete_site_preset($shortname);
@@ -161,7 +161,7 @@
         if (!$fullname) {
             $presetdir = $CFG->tempdir.'/forms/'.required_param('directory', PARAM_FILE);
             if (!file_exists($presetdir) || !is_dir($presetdir)) {
-                print_error('cannotimport');
+                throw new \moodle_exception('cannotimport');
             }
             $importer = new data_preset_upload_importer($course, $cm, $data, $presetdir);
         } else {
diff --git a/mod/data/tabs.php b/mod/data/tabs.php
index 62b2b88d5615b..8d8942a9c2e95 100644
--- a/mod/data/tabs.php
+++ b/mod/data/tabs.php
@@ -27,7 +27,7 @@
 
 
     if (empty($currenttab) or empty($data) or empty($course)) {
-        print_error('cannotcallscript');
+        throw new \moodle_exception('cannotcallscript');
     }
 
     $context = context_module::instance($cm->id);
diff --git a/mod/data/templates.php b/mod/data/templates.php
index e035259ae9ca9..733c175919b11 100644
--- a/mod/data/templates.php
+++ b/mod/data/templates.php
@@ -36,25 +36,25 @@
 if ($id) {
     $url->param('id', $id);
     if (! $cm = get_coursemodule_from_id('data', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record('course', array('id'=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $data = $DB->get_record('data', array('id'=>$cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
 } else {
     $url->param('d', $d);
     if (! $data = $DB->get_record('data', array('id'=>$d))) {
-        print_error('invalidid', 'data');
+        throw new \moodle_exception('invalidid', 'data');
     }
     if (! $course = $DB->get_record('course', array('id'=>$data->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('data', $data->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
diff --git a/mod/data/view.php b/mod/data/view.php
index 3947545bac6b1..dbca184b2b152 100644
--- a/mod/data/view.php
+++ b/mod/data/view.php
@@ -45,38 +45,38 @@
 
 if ($id) {
     if (! $cm = get_coursemodule_from_id('data', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record('course', array('id'=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $data = $DB->get_record('data', array('id'=>$cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     $record = NULL;
 
 } else if ($rid) {
     if (! $record = $DB->get_record('data_records', array('id'=>$rid))) {
-        print_error('invalidrecord', 'data');
+        throw new \moodle_exception('invalidrecord', 'data');
     }
     if (! $data = $DB->get_record('data', array('id'=>$record->dataid))) {
-        print_error('invalidid', 'data');
+        throw new \moodle_exception('invalidid', 'data');
     }
     if (! $course = $DB->get_record('course', array('id'=>$data->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('data', $data->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else {   // We must have $d
     if (! $data = $DB->get_record('data', array('id'=>$d))) {
-        print_error('invalidid', 'data');
+        throw new \moodle_exception('invalidid', 'data');
     }
     if (! $course = $DB->get_record('course', array('id'=>$data->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('data', $data->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     $record = NULL;
 }
@@ -266,7 +266,7 @@
 
 // Detect entries not approved yet and show hint instead of not found error.
 if ($record and !data_can_view_record($data, $record, $currentgroup, $canmanageentries)) {
-    print_error('notapproved', 'data');
+    throw new \moodle_exception('notapproved', 'data');
 }
 
 // Do we need to show a link to the RSS feed for the records?
diff --git a/mod/feedback/analysis.php b/mod/feedback/analysis.php
index e662c08c256fa..5641925d6280d 100644
--- a/mod/feedback/analysis.php
+++ b/mod/feedback/analysis.php
@@ -41,7 +41,7 @@
 $context = context_module::instance($cm->id);
 
 if (!$feedbackstructure->can_view_analysis()) {
-    print_error('error');
+    throw new \moodle_exception('error');
 }
 
 /// Print the page header
diff --git a/mod/feedback/analysis_course.php b/mod/feedback/analysis_course.php
index c7b57f846ba26..787d059aef861 100644
--- a/mod/feedback/analysis_course.php
+++ b/mod/feedback/analysis_course.php
@@ -53,7 +53,7 @@
 $feedback = $PAGE->activityrecord;
 
 if (!($feedback->publish_stats OR has_capability('mod/feedback:viewreports', $context))) {
-    print_error('error');
+    throw new \moodle_exception('error');
 }
 
 $feedbackstructure = new mod_feedback_structure($feedback, $PAGE->cm, $courseid);
diff --git a/mod/feedback/analysis_to_excel.php b/mod/feedback/analysis_to_excel.php
index aafcda049b65a..24adeb82d448a 100644
--- a/mod/feedback/analysis_to_excel.php
+++ b/mod/feedback/analysis_to_excel.php
@@ -49,7 +49,7 @@
 // Get the questions (item-names).
 $feedbackstructure = new mod_feedback_structure($feedback, $cm, $course->id);
 if (!$items = $feedbackstructure->get_items(true)) {
-    print_error('no_items_available_yet', 'feedback', $cm->url);
+    throw new \moodle_exception('no_items_available_yet', 'feedback', $cm->url);
 }
 
 $mygroupid = groups_get_activity_group($cm);
diff --git a/mod/feedback/classes/completion.php b/mod/feedback/classes/completion.php
index 89ec15a83c4cc..0aa5c1754d2f6 100644
--- a/mod/feedback/classes/completion.php
+++ b/mod/feedback/classes/completion.php
@@ -719,7 +719,7 @@ public function process_page($gopage, $gopreviouspage = false) {
             // Form was submitted (skip validation for "Previous page" button).
             $data = $this->form->get_submitted_data();
             if (!isset($SESSION->feedback->is_started) OR !$SESSION->feedback->is_started == true) {
-                print_error('error', '', $CFG->wwwroot.'/course/view.php?id='.$this->courseid);
+                throw new \moodle_exception('error', '', $CFG->wwwroot.'/course/view.php?id='.$this->courseid);
             }
             $this->save_response_tmp($data);
             if (!empty($data->savevalues) || !empty($data->gonextpage)) {
diff --git a/mod/feedback/complete.php b/mod/feedback/complete.php
index c56bfa301301d..855b798e7967e 100644
--- a/mod/feedback/complete.php
+++ b/mod/feedback/complete.php
@@ -61,7 +61,7 @@
 }
 
 if (!$feedbackcompletion->can_complete()) {
-    print_error('error');
+    throw new \moodle_exception('error');
 }
 
 $PAGE->navbar->add(get_string('feedback:complete', 'feedback'));
diff --git a/mod/feedback/edit.php b/mod/feedback/edit.php
index af956c27a2f5d..cfee4484bdf6b 100644
--- a/mod/feedback/edit.php
+++ b/mod/feedback/edit.php
@@ -30,7 +30,7 @@
 $id = required_param('id', PARAM_INT);
 
 if (($formdata = data_submitted()) AND !confirm_sesskey()) {
-    print_error('invalidsesskey');
+    throw new \moodle_exception('invalidsesskey');
 }
 
 $switchitemrequired = optional_param('switchitemrequired', false, PARAM_INT);
diff --git a/mod/feedback/edit_item.php b/mod/feedback/edit_item.php
index 1b5c74bad384f..713397349a4b7 100644
--- a/mod/feedback/edit_item.php
+++ b/mod/feedback/edit_item.php
@@ -65,7 +65,7 @@
 //get the existing item or create it
 // $formdata->itemid = isset($formdata->itemid) ? $formdata->itemid : NULL;
 if (!$typ || !file_exists($CFG->dirroot.'/mod/feedback/item/'.$typ.'/lib.php')) {
-    print_error('typemissing', 'feedback', $editurl->out(false));
+    throw new \moodle_exception('typemissing', 'feedback', $editurl->out(false));
 }
 
 require_once($CFG->dirroot.'/mod/feedback/item/'.$typ.'/lib.php');
diff --git a/mod/feedback/export.php b/mod/feedback/export.php
index 6f6672817ec3c..19f5b614a0a03 100644
--- a/mod/feedback/export.php
+++ b/mod/feedback/export.php
@@ -36,15 +36,15 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('feedback', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if (! $feedback = $DB->get_record("feedback", array("id"=>$cm->instance))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $context = context_module::instance($cm->id);
@@ -55,7 +55,7 @@
 
 if ($action == 'exportfile') {
     if (!$exportdata = feedback_get_xml_data($feedback->id)) {
-        print_error('nodata');
+        throw new \moodle_exception('nodata');
     }
     @feedback_send_xml_data($exportdata, 'feedback_'.$feedback->id.'.xml');
     exit;
diff --git a/mod/feedback/import.php b/mod/feedback/import.php
index c14c30bc59929..78c19674be960 100644
--- a/mod/feedback/import.php
+++ b/mod/feedback/import.php
@@ -41,15 +41,15 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('feedback', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if (! $feedback = $DB->get_record("feedback", array("id"=>$cm->instance))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $context = context_module::instance($cm->id);
@@ -77,7 +77,7 @@
     $xmlcontent = $mform->get_file_content('choosefile');
 
     if (!$xmldata = feedback_load_xml_data($xmlcontent)) {
-        print_error('cannotloadxml', 'feedback', 'edit.php?id='.$id);
+        throw new \moodle_exception('cannotloadxml', 'feedback', 'edit.php?id='.$id);
     }
 
     $importerror = feedback_import_loaded_data($xmldata, $feedback->id);
diff --git a/mod/feedback/index.php b/mod/feedback/index.php
index d0f00645cf115..704b74a4e4620 100644
--- a/mod/feedback/index.php
+++ b/mod/feedback/index.php
@@ -32,7 +32,7 @@
 $PAGE->set_url($url);
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 $context = context_course::instance($course->id);
diff --git a/mod/feedback/item/captcha/print_captcha.php b/mod/feedback/item/captcha/print_captcha.php
index 9d5b109f5eb03..7d7e6d0447fbc 100644
--- a/mod/feedback/item/captcha/print_captcha.php
+++ b/mod/feedback/item/captcha/print_captcha.php
@@ -22,20 +22,20 @@
 
 if ($id) {
     if (! $cm = get_coursemodule_from_id('feedback', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
 
     if (! $feedback = $DB->get_record("feedback", array("id"=>$cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
 if (!isset($SESSION->feedback->item->captcha)) {
-    print_error('captchanotset', 'feedback');
+    throw new \moodle_exception('captchanotset', 'feedback');
 }
 
 $height = 40;
diff --git a/mod/feedback/lib.php b/mod/feedback/lib.php
index 86d10857fee10..b7e9344b57041 100644
--- a/mod/feedback/lib.php
+++ b/mod/feedback/lib.php
@@ -2800,7 +2800,7 @@ function feedback_encode_target_url($url) {
 function feedback_extend_settings_navigation(settings_navigation $settings, navigation_node $feedbacknode) {
     $hassecondary = $settings->get_page()->has_secondary_navigation();
     if (!$context = context_module::instance($settings->get_page()->cm->id, IGNORE_MISSING)) {
-        print_error('badcontext');
+        throw new \moodle_exception('badcontext');
     }
 
     if (has_capability('mod/feedback:edititems', $context)) {
diff --git a/mod/feedback/show_nonrespondents.php b/mod/feedback/show_nonrespondents.php
index b1c4d361c50c4..3d3088cabe104 100644
--- a/mod/feedback/show_nonrespondents.php
+++ b/mod/feedback/show_nonrespondents.php
@@ -50,13 +50,13 @@
 
 list ($course, $cm) = get_course_and_cm_from_cmid($id, 'feedback');
 if (! $feedback = $DB->get_record("feedback", array("id"=>$cm->instance))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 //this page only can be shown on nonanonymous feedbacks in courses
 //we should never reach this page
 if ($feedback->anonymous != FEEDBACK_ANONYMOUS_NO OR $feedback->course == SITEID) {
-    print_error('error');
+    throw new \moodle_exception('error');
 }
 
 $url = new moodle_url('/mod/feedback/show_nonrespondents.php', array('id'=>$cm->id));
@@ -73,7 +73,7 @@
 $actionbar = new \mod_feedback\output\responses_action_bar($cm->id, $url);
 
 if (($formdata = data_submitted()) AND !confirm_sesskey()) {
-    print_error('invalidsesskey');
+    throw new \moodle_exception('invalidsesskey');
 }
 
 require_capability('mod/feedback:viewreports', $context);
diff --git a/mod/folder/download_folder.php b/mod/folder/download_folder.php
index 63626e33de1d8..c04f474f3eeff 100644
--- a/mod/folder/download_folder.php
+++ b/mod/folder/download_folder.php
@@ -37,13 +37,13 @@
 
 $downloadable = folder_archive_available($folder, $cm);
 if (!$downloadable) {
-    print_error('cannotdownloaddir', 'repository');
+    throw new \moodle_exception('cannotdownloaddir', 'repository');
 }
 
 $fs = get_file_storage();
 $files = $fs->get_area_files($context->id, 'mod_folder', 'content');
 if (empty($files)) {
-    print_error('cannotdownloaddir', 'repository');
+    throw new \moodle_exception('cannotdownloaddir', 'repository');
 }
 
 // Log zip as downloaded.
diff --git a/mod/forum/discuss.php b/mod/forum/discuss.php
index fd1165993b624..8b969549dad96 100644
--- a/mod/forum/discuss.php
+++ b/mod/forum/discuss.php
@@ -107,31 +107,31 @@
     $return = $discussionviewurl->out(false);
 
     if (!$forumto = $DB->get_record('forum', ['id' => $move])) {
-        print_error('cannotmovetonotexist', 'forum', $return);
+        throw new \moodle_exception('cannotmovetonotexist', 'forum', $return);
     }
 
     if (!$capabilitymanager->can_move_discussions($USER)) {
         if ($forum->get_type() == 'single') {
-            print_error('cannotmovefromsingleforum', 'forum', $return);
+            throw new \moodle_exception('cannotmovefromsingleforum', 'forum', $return);
         } else {
-            print_error('nopermissions', 'error', $return, get_capability_string('mod/forum:movediscussions'));
+            throw new \moodle_exception('nopermissions', 'error', $return, get_capability_string('mod/forum:movediscussions'));
         }
     }
 
     if ($forumto->type == 'single') {
-        print_error('cannotmovetosingleforum', 'forum', $return);
+        throw new \moodle_exception('cannotmovetosingleforum', 'forum', $return);
     }
 
     // Get target forum cm and check it is visible to current user.
     $modinfo = get_fast_modinfo($course);
     $forums = $modinfo->get_instances_of('forum');
     if (!array_key_exists($forumto->id, $forums)) {
-        print_error('cannotmovetonotfound', 'forum', $return);
+        throw new \moodle_exception('cannotmovetonotfound', 'forum', $return);
     }
 
     $cmto = $forums[$forumto->id];
     if (!$cmto->uservisible) {
-        print_error('cannotmovenotvisible', 'forum', $return);
+        throw new \moodle_exception('cannotmovenotvisible', 'forum', $return);
     }
 
     $destinationctx = context_module::instance($cmto->id);
@@ -216,7 +216,7 @@
 // Pin or unpin discussion if requested.
 if ($pin !== -1 && confirm_sesskey()) {
     if (!$capabilitymanager->can_pin_discussions($USER)) {
-        print_error('nopermissions', 'error', $return, get_capability_string('mod/forum:pindiscussions'));
+        throw new \moodle_exception('nopermissions', 'error', $return, get_capability_string('mod/forum:pindiscussions'));
     }
 
     $params = ['context' => $modcontext, 'objectid' => $discussion->get_id(), 'other' => ['forumid' => $forum->get_id()]];
@@ -276,11 +276,11 @@
 
 $postvault = $vaultfactory->get_post_vault();
 if (!$post = $postvault->get_from_id($parent)) {
-    print_error("notexists", 'forum', "$CFG->wwwroot/mod/forum/view.php?f={$forum->get_id()}");
+    throw new \moodle_exception("notexists", 'forum', "$CFG->wwwroot/mod/forum/view.php?f={$forum->get_id()}");
 }
 
 if (!$capabilitymanager->can_view_post($USER, $discussion, $post)) {
-    print_error('noviewdiscussionspermission', 'forum', "$CFG->wwwroot/mod/forum/view.php?id={$forum->get_id()}");
+    throw new \moodle_exception('noviewdiscussionspermission', 'forum', "$CFG->wwwroot/mod/forum/view.php?id={$forum->get_id()}");
 }
 
 $istracked = forum_tp_is_tracked($forumrecord, $USER);
diff --git a/mod/forum/index.php b/mod/forum/index.php
index eb06638195f4b..2d89847f9944b 100644
--- a/mod/forum/index.php
+++ b/mod/forum/index.php
@@ -39,7 +39,7 @@
 
 if ($id) {
     if (!$course = $DB->get_record('course', array('id' => $id))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 } else {
     $course = get_site();
diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index 16c7f40a3f667..fc6f4a9cc6e7d 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -235,11 +235,11 @@ function forum_update_instance($forum, $mform) {
             forum_add_discussion($discussion, null, $message);
 
             if (! $discussion = $DB->get_record('forum_discussions', array('forum'=>$forum->id))) {
-                print_error('cannotadd', 'forum');
+                throw new \moodle_exception('cannotadd', 'forum');
             }
         }
         if (! $post = $DB->get_record('forum_posts', array('id'=>$discussion->firstpost))) {
-            print_error('cannotfindfirstpost', 'forum');
+            throw new \moodle_exception('cannotfindfirstpost', 'forum');
         }
 
         $cm         = get_coursemodule_from_instance('forum', $forum->id);
@@ -499,7 +499,7 @@ function forum_user_complete($course, $user, $mod, $forum) {
 
     if ($posts = forum_get_user_posts($forum->id, $user->id)) {
         if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $course->id)) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
         $context = context_module::instance($cm->id);
         $discussions = forum_get_user_involved_discussions($forum->id, $user->id);
@@ -1008,7 +1008,7 @@ function forum_get_readable_forums($userid, $courseid=0) {
     require_once($CFG->dirroot.'/course/lib.php');
 
     if (!$forummod = $DB->get_record('modules', array('name' => 'forum'))) {
-        print_error('notinstalled', 'forum');
+        throw new \moodle_exception('notinstalled', 'forum');
     }
 
     if ($courseid) {
@@ -2337,7 +2337,7 @@ function forum_print_discussion_header(&$post, $forum, $group = -1, $datestring
 
     if (empty($modcontext)) {
         if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
         $modcontext = context_module::instance($cm->id);
     }
@@ -3679,7 +3679,7 @@ function forum_user_can_post_discussion($forum, $currentgroup=null, $unused=-1,
     if (!$cm) {
         debugging('missing cm', DEBUG_DEVELOPER);
         if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
     }
 
@@ -3771,14 +3771,14 @@ function forum_user_can_post($forum, $discussion, $user=NULL, $cm=NULL, $course=
     if (!$cm) {
         debugging('missing cm', DEBUG_DEVELOPER);
         if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
     }
 
     if (!$course) {
         debugging('missing course', DEBUG_DEVELOPER);
         if (!$course = $DB->get_record('course', array('id' => $forum->course))) {
-            print_error('invalidcourseid');
+            throw new \moodle_exception('invalidcourseid');
         }
     }
 
@@ -3915,7 +3915,7 @@ function forum_user_can_see_discussion($forum, $discussion, $context, $user=NULL
         }
     }
     if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     if (!has_capability('mod/forum:viewdiscussion', $context)) {
@@ -3979,7 +3979,7 @@ function forum_user_can_see_post($forum, $discussion, $post, $user = null, $cm =
     if (!$cm) {
         debugging('missing cm', DEBUG_DEVELOPER);
         if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
     }
 
@@ -5129,7 +5129,7 @@ function forum_check_throttling($forum, $cm = null) {
  */
 function forum_check_blocking_threshold($thresholdwarning) {
     if (!empty($thresholdwarning) && !$thresholdwarning->canpost) {
-        print_error($thresholdwarning->errorcode,
+        throw new \moodle_exception($thresholdwarning->errorcode,
                     $thresholdwarning->module,
                     $thresholdwarning->link,
                     $thresholdwarning->additional);
@@ -5871,7 +5871,7 @@ function forum_get_posts_by_user($user, array $courses, $musthaveaccess = false,
             if (!is_viewing($coursecontext, $user) && !is_enrolled($coursecontext, $user)) {
                 // Need to have full access to a course to see the rest of own info
                 if ($musthaveaccess) {
-                    print_error('errorenrolmentrequired', 'forum');
+                    throw new \moodle_exception('errorenrolmentrequired', 'forum');
                 }
                 continue;
             }
@@ -5880,7 +5880,7 @@ function forum_get_posts_by_user($user, array $courses, $musthaveaccess = false,
             // if they don't we immediately have a problem.
             if (!can_access_course($course)) {
                 if ($musthaveaccess) {
-                    print_error('errorenrolmentrequired', 'forum');
+                    throw new \moodle_exception('errorenrolmentrequired', 'forum');
                 }
                 continue;
             }
@@ -5910,7 +5910,7 @@ function forum_get_posts_by_user($user, array $courses, $musthaveaccess = false,
                     // But they're not... if it was a specific course throw an error otherwise
                     // just skip this course so that it is not searched.
                     if ($musthaveaccess) {
-                        print_error("groupnotamember", '', $CFG->wwwroot."/course/view.php?id=$course->id");
+                        throw new \moodle_exception("groupnotamember", '', $CFG->wwwroot."/course/view.php?id=$course->id");
                     }
                     continue;
                 }
@@ -5930,7 +5930,7 @@ function forum_get_posts_by_user($user, array $courses, $musthaveaccess = false,
         // user doesn't have access to any courses is which the requested user has posted.
         // Although we do know at this point that the requested user has posts.
         if ($musthaveaccess) {
-            print_error('permissiondenied');
+            throw new \moodle_exception('permissiondenied');
         } else {
             return $return;
         }
diff --git a/mod/forum/markposts.php b/mod/forum/markposts.php
index 9cdfd8835c1a7..fe96e6628380d 100644
--- a/mod/forum/markposts.php
+++ b/mod/forum/markposts.php
@@ -41,15 +41,15 @@
 $PAGE->set_url($url);
 
 if (! $forum = $DB->get_record("forum", array("id" => $f))) {
-    print_error('invalidforumid', 'forum');
+    throw new \moodle_exception('invalidforumid', 'forum');
 }
 
 if (! $course = $DB->get_record("course", array("id" => $forum->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if (!$cm = get_coursemodule_from_instance("forum", $forum->id, $course->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $user = $USER;
@@ -79,7 +79,7 @@
 if ($mark == 'read') {
     if (!empty($d)) {
         if (! $discussion = $DB->get_record('forum_discussions', array('id'=> $d, 'forum'=> $forum->id))) {
-            print_error('invaliddiscussionid', 'forum');
+            throw new \moodle_exception('invaliddiscussionid', 'forum');
         }
 
         forum_tp_mark_discussion_read($user, $d);
diff --git a/mod/forum/post.php b/mod/forum/post.php
index 307e835db79bb..c00b947f7fe14 100644
--- a/mod/forum/post.php
+++ b/mod/forum/post.php
@@ -81,13 +81,13 @@
         // User is starting a new discussion in a forum.
         $forumentity = $forumvault->get_from_id($forum);
         if (empty($forumentity)) {
-            print_error('invalidforumid', 'forum');
+            throw new \moodle_exception('invalidforumid', 'forum');
         }
     } else if (!empty($reply)) {
         // User is writing a new reply.
         $forumentity = $forumvault->get_from_post_id($reply);
         if (empty($forumentity)) {
-            print_error('invalidparentpostid', 'forum');
+            throw new \moodle_exception('invalidparentpostid', 'forum');
         }
     }
 
@@ -95,7 +95,7 @@
     $modcontext = $forumentity->get_context();
     $course = $forumentity->get_course_record();
     if (!$cm = get_coursemodule_from_instance("forum", $forum->id, $course->id)) {
-        print_error("invalidcoursemodule");
+        throw new \moodle_exception("invalidcoursemodule");
     }
 
     $PAGE->set_cm($cm, $course, $forum);
@@ -118,14 +118,14 @@
     // User is starting a new discussion in a forum.
     $forumentity = $forumvault->get_from_id($forum);
     if (empty($forumentity)) {
-        print_error('invalidforumid', 'forum');
+        throw new \moodle_exception('invalidforumid', 'forum');
     }
 
     $capabilitymanager = $managerfactory->get_capability_manager($forumentity);
     $forum = $forumdatamapper->to_legacy_object($forumentity);
     $course = $forumentity->get_course_record();
     if (!$cm = get_coursemodule_from_instance("forum", $forum->id, $course->id)) {
-        print_error("invalidcoursemodule");
+        throw new \moodle_exception("invalidcoursemodule");
     }
 
     // Retrieve the contexts.
@@ -148,7 +148,7 @@
                 }
             }
         }
-        print_error('nopostforum', 'forum');
+        throw new \moodle_exception('nopostforum', 'forum');
     }
 
     if (!$cm->visible and !has_capability('moodle/course:viewhiddenactivities', $modcontext)) {
@@ -182,17 +182,17 @@
 
     $parententity = $postvault->get_from_id($reply);
     if (empty($parententity)) {
-        print_error('invalidparentpostid', 'forum');
+        throw new \moodle_exception('invalidparentpostid', 'forum');
     }
 
     $discussionentity = $discussionvault->get_from_id($parententity->get_discussion_id());
     if (empty($discussionentity)) {
-        print_error('notpartofdiscussion', 'forum');
+        throw new \moodle_exception('notpartofdiscussion', 'forum');
     }
 
     $forumentity = $forumvault->get_from_id($discussionentity->get_forum_id());
     if (empty($forumentity)) {
-        print_error('invalidforumid', 'forum');
+        throw new \moodle_exception('invalidforumid', 'forum');
     }
 
     $capabilitymanager = $managerfactory->get_capability_manager($forumentity);
@@ -204,7 +204,7 @@
     $coursecontext = context_course::instance($course->id);
 
     if (!$cm = get_coursemodule_from_instance("forum", $forum->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     // Ensure lang, theme, etc. is set up properly. MDL-6926.
@@ -225,7 +225,7 @@
                 redirect(new moodle_url('/mod/forum/discuss.php', array('d' => $discussion->id)));
             }
         }
-        print_error('nopostforum', 'forum');
+        throw new \moodle_exception('nopostforum', 'forum');
     }
 
     // Make sure user can post here.
@@ -236,20 +236,20 @@
     }
     if ($groupmode == SEPARATEGROUPS and !has_capability('moodle/site:accessallgroups', $modcontext)) {
         if ($discussion->groupid == -1) {
-            print_error('nopostforum', 'forum');
+            throw new \moodle_exception('nopostforum', 'forum');
         } else {
             if (!groups_is_member($discussion->groupid)) {
-                print_error('nopostforum', 'forum');
+                throw new \moodle_exception('nopostforum', 'forum');
             }
         }
     }
 
     if (!$cm->visible and !has_capability('moodle/course:viewhiddenactivities', $modcontext)) {
-        print_error("activityiscurrentlyhidden");
+        throw new \moodle_exception("activityiscurrentlyhidden");
     }
 
     if ($parententity->is_private_reply()) {
-        print_error('cannotreplytoprivatereply', 'forum');
+        throw new \moodle_exception('cannotreplytoprivatereply', 'forum');
     }
 
     // We always are going to honor the preferred format. We are creating a new post.
@@ -292,7 +292,7 @@
 
     $postentity = $postvault->get_from_id($edit);
     if (empty($postentity)) {
-        print_error('invalidpostid', 'forum');
+        throw new \moodle_exception('invalidpostid', 'forum');
     }
     if ($postentity->has_parent()) {
         $parententity = $postvault->get_from_id($postentity->get_parent_id());
@@ -301,12 +301,12 @@
 
     $discussionentity = $discussionvault->get_from_id($postentity->get_discussion_id());
     if (empty($discussionentity)) {
-        print_error('notpartofdiscussion', 'forum');
+        throw new \moodle_exception('notpartofdiscussion', 'forum');
     }
 
     $forumentity = $forumvault->get_from_id($discussionentity->get_forum_id());
     if (empty($forumentity)) {
-        print_error('invalidforumid', 'forum');
+        throw new \moodle_exception('invalidforumid', 'forum');
     }
 
     $capabilitymanager = $managerfactory->get_capability_manager($forumentity);
@@ -318,7 +318,7 @@
     $coursecontext = context_course::instance($course->id);
 
     if (!$cm = get_coursemodule_from_instance("forum", $forum->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     $PAGE->set_cm($cm, $course, $forum);
@@ -326,12 +326,12 @@
     if (!($forum->type == 'news' && !$post->parent && $discussion->timestart > time())) {
         if (((time() - $post->created) > $CFG->maxeditingtime) and
             !has_capability('mod/forum:editanypost', $modcontext)) {
-            print_error('maxtimehaspassed', 'forum', '', format_time($CFG->maxeditingtime));
+            throw new \moodle_exception('maxtimehaspassed', 'forum', '', format_time($CFG->maxeditingtime));
         }
     }
     if (($post->userid <> $USER->id) and
         !has_capability('mod/forum:editanypost', $modcontext)) {
-        print_error('cannoteditposts', 'forum');
+        throw new \moodle_exception('cannoteditposts', 'forum');
     }
 
     // Load up the $post variable.
@@ -353,17 +353,17 @@
 
     $postentity = $postvault->get_from_id($delete);
     if (empty($postentity)) {
-        print_error('invalidpostid', 'forum');
+        throw new \moodle_exception('invalidpostid', 'forum');
     }
 
     $discussionentity = $discussionvault->get_from_id($postentity->get_discussion_id());
     if (empty($discussionentity)) {
-        print_error('notpartofdiscussion', 'forum');
+        throw new \moodle_exception('notpartofdiscussion', 'forum');
     }
 
     $forumentity = $forumvault->get_from_id($discussionentity->get_forum_id());
     if (empty($forumentity)) {
-        print_error('invalidforumid', 'forum');
+        throw new \moodle_exception('invalidforumid', 'forum');
     }
 
     $capabilitymanager = $managerfactory->get_capability_manager($forumentity);
@@ -510,17 +510,17 @@
 
     $postentity = $postvault->get_from_id($prune);
     if (empty($postentity)) {
-        print_error('invalidpostid', 'forum');
+        throw new \moodle_exception('invalidpostid', 'forum');
     }
 
     $discussionentity = $discussionvault->get_from_id($postentity->get_discussion_id());
     if (empty($discussionentity)) {
-        print_error('notpartofdiscussion', 'forum');
+        throw new \moodle_exception('notpartofdiscussion', 'forum');
     }
 
     $forumentity = $forumvault->get_from_id($discussionentity->get_forum_id());
     if (empty($forumentity)) {
-        print_error('invalidforumid', 'forum');
+        throw new \moodle_exception('invalidforumid', 'forum');
     }
 
     $capabilitymanager = $managerfactory->get_capability_manager($forumentity);
@@ -532,7 +532,7 @@
     $coursecontext = context_course::instance($course->id);
 
     if (!$cm = get_coursemodule_from_instance("forum", $forum->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     if (!$postentity->has_parent()) {
@@ -658,7 +658,7 @@
     echo $OUTPUT->footer();
     die;
 } else {
-    print_error('unknowaction');
+    throw new \moodle_exception('unknowaction');
 
 }
 
@@ -668,7 +668,7 @@
 
 if (isguestuser()) {
     // Just in case.
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 $thresholdwarning = forum_check_throttling($forum, $cm);
@@ -847,7 +847,7 @@
         $updatepost = $fromform;
         $updatepost->forum = $forum->id;
         if (!forum_update_post($updatepost, $mformpost)) {
-            print_error("couldnotupdate", "forum", $errordestination);
+            throw new \moodle_exception("couldnotupdate", "forum", $errordestination);
         }
 
         forum_trigger_post_updated_event($post, $discussion, $modcontext, $forum);
@@ -933,7 +933,7 @@
             );
 
         } else {
-            print_error("couldnotadd", "forum", $errordestination);
+            throw new \moodle_exception("couldnotadd", "forum", $errordestination);
         }
         exit;
 
@@ -993,7 +993,7 @@
 
         foreach ($groupstopostto as $group) {
             if (!$capabilitymanager->can_create_discussions($USER, $groupid)) {
-                print_error('cannotcreatediscussion', 'forum');
+                throw new \moodle_exception('cannotcreatediscussion', 'forum');
             }
 
             $discussion->groupid = $group;
@@ -1020,7 +1020,7 @@
 
                 $subscribemessage = forum_post_subscription($fromform, $forum, $discussion);
             } else {
-                print_error("couldnotadd", "forum", $errordestination);
+                throw new \moodle_exception("couldnotadd", "forum", $errordestination);
             }
         }
 
@@ -1109,11 +1109,11 @@
 
 // Checkup.
 if (!empty($parententity) && !$capabilitymanager->can_view_post($USER, $discussionentity, $parententity)) {
-    print_error('cannotreply', 'forum');
+    throw new \moodle_exception('cannotreply', 'forum');
 }
 
 if (empty($parententity) && empty($edit) && !$capabilitymanager->can_create_discussions($USER, $groupid)) {
-    print_error('cannotcreatediscussion', 'forum');
+    throw new \moodle_exception('cannotcreatediscussion', 'forum');
 }
 
 if (!empty($discussionentity) && 'qanda' == $forumentity->get_type()) {
diff --git a/mod/forum/report/summary/index.php b/mod/forum/report/summary/index.php
index 31e794d947189..dd3279f062c12 100644
--- a/mod/forum/report/summary/index.php
+++ b/mod/forum/report/summary/index.php
@@ -25,7 +25,7 @@
 require_once("../../../../config.php");
 
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 $courseid = required_param('courseid', PARAM_INT);
diff --git a/mod/forum/rsslib.php b/mod/forum/rsslib.php
index b99e1d36fadc1..b0251f3c62ec0 100644
--- a/mod/forum/rsslib.php
+++ b/mod/forum/rsslib.php
@@ -325,7 +325,7 @@ function forum_rss_feed_contents($forum, $sql, $params, $context) {
     }
 
     if (!$cm = get_coursemodule_from_instance('forum', $forum->id, $forum->course)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     $formatoptions = new stdClass();
diff --git a/mod/forum/search.php b/mod/forum/search.php
index e5b17928b4926..e4432db915e80 100644
--- a/mod/forum/search.php
+++ b/mod/forum/search.php
@@ -120,7 +120,7 @@
 }
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_course_login($course);
@@ -284,12 +284,12 @@
     // Replace the simple subject with the three items forum name -> thread name -> subject
     // (if all three are appropriate) each as a link.
     if (!isset($discussionsbyid[$post->discussion])) {
-        print_error('invaliddiscussionid', 'forum');
+        throw new \moodle_exception('invaliddiscussionid', 'forum');
     }
 
     $discussion = $discussionsbyid[$post->discussion];
     if (!isset($forumsbyid[$discussion->get_forum_id()])) {
-        print_error('invalidforumid', 'forum');
+        throw new \moodle_exception('invalidforumid', 'forum');
     }
 
     $forum = $forumsbyid[$discussion->get_forum_id()];
diff --git a/mod/forum/settracking.php b/mod/forum/settracking.php
index 7440a4a59c962..276f673c40786 100644
--- a/mod/forum/settracking.php
+++ b/mod/forum/settracking.php
@@ -32,15 +32,15 @@
 require_sesskey();
 
 if (! $forum = $DB->get_record("forum", array("id" => $id))) {
-    print_error('invalidforumid', 'forum');
+    throw new \moodle_exception('invalidforumid', 'forum');
 }
 
 if (! $course = $DB->get_record("course", array("id" => $forum->course))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $cm = get_coursemodule_from_instance("forum", $forum->id, $course->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 require_login($course, false, $cm);
 $returnpageurl = new moodle_url('/mod/forum/' . $returnpage, array('id' => $course->id, 'f' => $forum->id));
@@ -66,7 +66,7 @@
         $event->trigger();
         redirect($returnto, get_string("nownottracking", "forum", $info), 1);
     } else {
-        print_error('cannottrack', '', get_local_referer(false));
+        throw new \moodle_exception('cannottrack', '', get_local_referer(false));
     }
 
 } else { // subscribe
@@ -75,6 +75,6 @@
         $event->trigger();
         redirect($returnto, get_string("nowtracking", "forum", $info), 1);
     } else {
-        print_error('cannottrack', '', get_local_referer(false));
+        throw new \moodle_exception('cannottrack', '', get_local_referer(false));
     }
 }
\ No newline at end of file
diff --git a/mod/forum/subscribe.php b/mod/forum/subscribe.php
index 6ee62d8de419b..8cd92c44e38c2 100644
--- a/mod/forum/subscribe.php
+++ b/mod/forum/subscribe.php
@@ -55,7 +55,7 @@
 if (!is_null($discussionid)) {
     $url->param('d', $discussionid);
     if (!$discussion = $DB->get_record('forum_discussions', array('id' => $discussionid, 'forum' => $id))) {
-        print_error('invaliddiscussionid', 'forum');
+        throw new \moodle_exception('invaliddiscussionid', 'forum');
     }
 }
 $PAGE->set_url($url);
@@ -68,7 +68,7 @@
 if ($user) {
     require_sesskey();
     if (!has_capability('mod/forum:managesubscriptions', $context)) {
-        print_error('nopermissiontosubscribe', 'forum');
+        throw new \moodle_exception('nopermissiontosubscribe', 'forum');
     }
     $user = $DB->get_record('user', array('id' => $user), '*', MUST_EXIST);
 } else {
@@ -86,7 +86,7 @@
 // For a user to subscribe when a groupmode is set, they must have access to at least one group.
 if ($groupmode && !$issubscribed && !has_capability('moodle/site:accessallgroups', $context)) {
     if (!groups_get_all_groups($course->id, $USER->id)) {
-        print_error('cannotsubscribe', 'forum');
+        throw new \moodle_exception('cannotsubscribe', 'forum');
     }
 }
 
@@ -170,7 +170,7 @@
             );
             break;
         default:
-            print_error(get_string('invalidforcesubscribe', 'forum'));
+            throw new \moodle_exception(get_string('invalidforcesubscribe', 'forum'));
     }
 }
 
@@ -214,7 +214,7 @@
                 \core\output\notification::NOTIFY_SUCCESS
             );
         } else {
-            print_error('cannotunsubscribe', 'forum', get_local_referer(false));
+            throw new \moodle_exception('cannotunsubscribe', 'forum', get_local_referer(false));
         }
     } else {
         if (\mod_forum\subscriptions::unsubscribe_user_from_discussion($user->id, $discussion, $context)) {
@@ -226,16 +226,16 @@
                 \core\output\notification::NOTIFY_SUCCESS
             );
         } else {
-            print_error('cannotunsubscribe', 'forum', get_local_referer(false));
+            throw new \moodle_exception('cannotunsubscribe', 'forum', get_local_referer(false));
         }
     }
 
 } else {  // subscribe
     if (\mod_forum\subscriptions::subscription_disabled($forum) && !has_capability('mod/forum:managesubscriptions', $context)) {
-        print_error('disallowsubscribe', 'forum', get_local_referer(false));
+        throw new \moodle_exception('disallowsubscribe', 'forum', get_local_referer(false));
     }
     if (!has_capability('mod/forum:viewdiscussion', $context)) {
-        print_error('noviewdiscussionspermission', 'forum', get_local_referer(false));
+        throw new \moodle_exception('noviewdiscussionspermission', 'forum', get_local_referer(false));
     }
     if (is_null($sesskey)) {
         // We came here via link in email.
diff --git a/mod/forum/subscribers.php b/mod/forum/subscribers.php
index 8c38fa1f7bd1c..408b281c80d1e 100644
--- a/mod/forum/subscribers.php
+++ b/mod/forum/subscribers.php
@@ -53,7 +53,7 @@
 
 $context = context_module::instance($cm->id);
 if (!has_capability('mod/forum:viewsubscribers', $context)) {
-    print_error('nopermissiontosubscribe', 'forum');
+    throw new \moodle_exception('nopermissiontosubscribe', 'forum');
 }
 
 unset($SESSION->fromdiscussion);
@@ -78,20 +78,20 @@
     $unsubscribe = (bool)optional_param('unsubscribe', false, PARAM_RAW);
     /** It has to be one or the other, not both or neither */
     if (!($subscribe xor $unsubscribe)) {
-        print_error('invalidaction');
+        throw new \moodle_exception('invalidaction');
     }
     if ($subscribe) {
         $users = $subscriberselector->get_selected_users();
         foreach ($users as $user) {
             if (!\mod_forum\subscriptions::subscribe_user($user->id, $forum)) {
-                print_error('cannotaddsubscriber', 'forum', '', $user->id);
+                throw new \moodle_exception('cannotaddsubscriber', 'forum', '', $user->id);
             }
         }
     } else if ($unsubscribe) {
         $users = $existingselector->get_selected_users();
         foreach ($users as $user) {
             if (!\mod_forum\subscriptions::unsubscribe_user($user->id, $forum)) {
-                print_error('cannotremovesubscriber', 'forum', '', $user->id);
+                throw new \moodle_exception('cannotremovesubscriber', 'forum', '', $user->id);
             }
         }
     }
diff --git a/mod/forum/user.php b/mod/forum/user.php
index 8fa33aa1294dc..c347d5c851fa0 100644
--- a/mod/forum/user.php
+++ b/mod/forum/user.php
@@ -69,7 +69,7 @@
 if (isguestuser($user)) {
     // The guest user cannot post, so it is not possible to view any posts.
     // May as well just bail aggressively here.
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 // Make sure the user has not been deleted
 if ($user->deleted) {
diff --git a/mod/forum/view.php b/mod/forum/view.php
index fd7c14c132faf..bd2faba3e399f 100644
--- a/mod/forum/view.php
+++ b/mod/forum/view.php
@@ -45,7 +45,7 @@
 $sortorder = optional_param('o', null, PARAM_INT);
 
 if (!$cmid && !$forumid) {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 if ($cmid) {
diff --git a/mod/glossary/deleteentry.php b/mod/glossary/deleteentry.php
index c3f676d48ea16..e28c673a27e3e 100644
--- a/mod/glossary/deleteentry.php
+++ b/mod/glossary/deleteentry.php
@@ -28,27 +28,27 @@
 
 
 if (! $cm = get_coursemodule_from_id('glossary', $id)) {
-    print_error("invalidcoursemodule");
+    throw new \moodle_exception("invalidcoursemodule");
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if (! $entry = $DB->get_record("glossary_entries", array("id"=>$entry))) {
-    print_error('invalidentry');
+    throw new \moodle_exception('invalidentry');
 }
 
 // Permission checks are based on the course module instance so make sure it is correct.
 if ($cm->instance != $entry->glossaryid) {
-    print_error('invalidentry');
+    throw new \moodle_exception('invalidentry');
 }
 
 require_login($course, false, $cm);
 $context = context_module::instance($cm->id);
 
 if (! $glossary = $DB->get_record("glossary", array("id"=>$cm->instance))) {
-    print_error('invalidid', 'glossary');
+    throw new \moodle_exception('invalidid', 'glossary');
 }
 
 // Throws an exception if the user cannot delete the entry.
diff --git a/mod/glossary/edit.php b/mod/glossary/edit.php
index d48d4e64d46cb..6c16aea93b6b3 100644
--- a/mod/glossary/edit.php
+++ b/mod/glossary/edit.php
@@ -8,11 +8,11 @@
 $id   = optional_param('id', 0, PARAM_INT);           // EntryID
 
 if (!$cm = get_coursemodule_from_id('glossary', $cmid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (!$course = $DB->get_record('course', array('id'=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 require_login($course, false, $cm);
@@ -20,7 +20,7 @@
 $context = context_module::instance($cm->id);
 
 if (!$glossary = $DB->get_record('glossary', array('id'=>$cm->instance))) {
-    print_error('invalidid', 'glossary');
+    throw new \moodle_exception('invalidid', 'glossary');
 }
 
 $url = new moodle_url('/mod/glossary/edit.php', array('cmid'=>$cm->id));
@@ -31,11 +31,11 @@
 
 if ($id) { // if entry is specified
     if (isguestuser()) {
-        print_error('guestnoedit', 'glossary', "$CFG->wwwroot/mod/glossary/view.php?id=$cmid");
+        throw new \moodle_exception('guestnoedit', 'glossary', "$CFG->wwwroot/mod/glossary/view.php?id=$cmid");
     }
 
     if (!$entry = $DB->get_record('glossary_entries', array('id'=>$id, 'glossaryid'=>$glossary->id))) {
-        print_error('invalidentry');
+        throw new \moodle_exception('invalidentry');
     }
 
     // Check if the user can update the entry (trigger exception if he can't).
diff --git a/mod/glossary/editcategories.php b/mod/glossary/editcategories.php
index 079c86f1d3649..e239204bf8ee9 100644
--- a/mod/glossary/editcategories.php
+++ b/mod/glossary/editcategories.php
@@ -39,25 +39,25 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('glossary', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if (! $glossary = $DB->get_record("glossary", array("id"=>$cm->instance))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if ($hook > 0) {
     if ($category = $DB->get_record("glossary_categories", array("id"=>$hook))) {
         //Check it belongs to the same glossary
         if ($category->glossaryid != $glossary->id) {
-            print_error('invalidid', 'glossary');
+            throw new \moodle_exception('invalidid', 'glossary');
         }
     } else {
-        print_error('invalidcategoryid');
+        throw new \moodle_exception('invalidcategoryid');
     }
 }
 
diff --git a/mod/glossary/export.php b/mod/glossary/export.php
index 403c83f8f459e..9cddfc29aa07f 100644
--- a/mod/glossary/export.php
+++ b/mod/glossary/export.php
@@ -20,15 +20,15 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('glossary', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if (! $glossary = $DB->get_record("glossary", array("id"=>$cm->instance))) {
-    print_error('invalidid', 'glossary');
+    throw new \moodle_exception('invalidid', 'glossary');
 }
 
 require_login($course, false, $cm);
diff --git a/mod/glossary/exportentry.php b/mod/glossary/exportentry.php
index 3acd9f722d348..0b345dab43233 100644
--- a/mod/glossary/exportentry.php
+++ b/mod/glossary/exportentry.php
@@ -18,27 +18,27 @@
 $PAGE->set_url($url);
 
 if (!$entry = $DB->get_record('glossary_entries', array('id'=>$id))) {
-    print_error('invalidentry');
+    throw new \moodle_exception('invalidentry');
 }
 
 if ($entry->sourceglossaryid) {
     //already exported
     if (!$cm = get_coursemodule_from_id('glossary', $entry->sourceglossaryid)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     redirect('view.php?id='.$cm->id.'&amp;mode=entry&amp;hook='.$entry->id);
 }
 
 if (!$cm = get_coursemodule_from_instance('glossary', $entry->glossaryid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (!$glossary = $DB->get_record('glossary', array('id'=>$cm->instance))) {
-    print_error('invalidid', 'glossary');
+    throw new \moodle_exception('invalidid', 'glossary');
 }
 
 if (!$course = $DB->get_record('course', array('id'=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 require_course_login($course->id, true, $cm);
@@ -53,14 +53,14 @@
 }
 
 if (!$maincm = get_coursemodule_from_instance('glossary', $mainglossary->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $context     = context_module::instance($cm->id);
 $maincontext = context_module::instance($maincm->id);
 
 if (!$course = $DB->get_record('course', array('id'=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 
diff --git a/mod/glossary/formats.php b/mod/glossary/formats.php
index ca0e19770af8c..01fafce6be888 100644
--- a/mod/glossary/formats.php
+++ b/mod/glossary/formats.php
@@ -18,7 +18,7 @@
 admin_externalpage_setup('managemodules'); // this is hacky, tehre should be a special hidden page for it
 
 if ( !$displayformat = $DB->get_record("glossary_formats", array("id"=>$id))) {
-    print_error('invalidglossaryformat', 'glossary');
+    throw new \moodle_exception('invalidglossaryformat', 'glossary');
 }
 
 $form = data_submitted();
diff --git a/mod/glossary/import.php b/mod/glossary/import.php
index 942c5372e4591..f1bcbbd80406a 100644
--- a/mod/glossary/import.php
+++ b/mod/glossary/import.php
@@ -21,15 +21,15 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('glossary', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if (! $glossary = $DB->get_record("glossary", array("id"=>$cm->instance))) {
-    print_error('invalidid', 'glossary');
+    throw new \moodle_exception('invalidid', 'glossary');
 }
 
 require_login($course, false, $cm);
@@ -185,7 +185,7 @@
         $newentry->concept = trim($xmlentry['#']['CONCEPT'][0]['#']);
         $definition = $xmlentry['#']['DEFINITION'][0]['#'];
         if (!is_string($definition)) {
-            print_error('errorparsingxml', 'glossary');
+            throw new \moodle_exception('errorparsingxml', 'glossary');
         }
         $newentry->definition = trusttext_strip($definition);
         if ( isset($xmlentry['#']['CASESENSITIVE'][0]['#']) ) {
diff --git a/mod/glossary/index.php b/mod/glossary/index.php
index c432477adef2f..5024577473312 100644
--- a/mod/glossary/index.php
+++ b/mod/glossary/index.php
@@ -13,7 +13,7 @@
 $PAGE->set_url('/mod/glossary/index.php', array('id'=>$id));
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_course_login($course);
diff --git a/mod/glossary/lib.php b/mod/glossary/lib.php
index 47f39448d099a..49970dcfbe409 100644
--- a/mod/glossary/lib.php
+++ b/mod/glossary/lib.php
@@ -83,7 +83,7 @@ function glossary_add_instance($glossary) {
     //Check displayformat is a valid one
     $formats = get_list_of_plugins('mod/glossary/formats','TEMPLATE');
     if (!in_array($glossary->displayformat, $formats)) {
-        print_error('unknowformat', '', '', $glossary->displayformat);
+        throw new \moodle_exception('unknowformat', '', '', $glossary->displayformat);
     }
 
     $returnid = $DB->insert_record("glossary", $glossary);
@@ -130,7 +130,7 @@ function glossary_update_instance($glossary) {
     //Check displayformat is a valid one
     $formats = get_list_of_plugins('mod/glossary/formats','TEMPLATE');
     if (!in_array($glossary->displayformat, $formats)) {
-        print_error('unknowformat', '', '', $glossary->displayformat);
+        throw new \moodle_exception('unknowformat', '', '', $glossary->displayformat);
     }
 
     $DB->update_record("glossary", $glossary);
@@ -2189,13 +2189,13 @@ function glossary_print_dynaentry($courseid, $entries, $displayformat = -1) {
     if ( $entries ) {
         foreach ( $entries as $entry ) {
             if (! $glossary = $DB->get_record('glossary', array('id'=>$entry->glossaryid))) {
-                print_error('invalidid', 'glossary');
+                throw new \moodle_exception('invalidid', 'glossary');
             }
             if (! $course = $DB->get_record('course', array('id'=>$glossary->course))) {
-                print_error('coursemisconf');
+                throw new \moodle_exception('coursemisconf');
             }
             if (!$cm = get_coursemodule_from_instance('glossary', $entry->glossaryid, $glossary->course) ) {
-                print_error('invalidid', 'glossary');
+                throw new \moodle_exception('invalidid', 'glossary');
             }
 
             //If displayformat is present, override glossary->displayformat
@@ -4369,7 +4369,7 @@ function mod_glossary_delete_entry($entry, $glossary, $cm, $context, $course, $h
     // If it is an imported entry, just delete the relation.
     if ($entry->sourceglossaryid) {
         if (!$newcm = get_coursemodule_from_instance('glossary', $entry->sourceglossaryid)) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
         $newcontext = context_module::instance($newcm->id);
 
diff --git a/mod/glossary/print.php b/mod/glossary/print.php
index 292d892c5c87b..ac82e5030620d 100644
--- a/mod/glossary/print.php
+++ b/mod/glossary/print.php
@@ -37,15 +37,15 @@
 $PAGE->set_url($url);
 
 if (! $cm = get_coursemodule_from_id('glossary', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if (! $glossary = $DB->get_record("glossary", array("id"=>$cm->instance))) {
-    print_error('invalidid', 'glossary');
+    throw new \moodle_exception('invalidid', 'glossary');
 }
 
 if ($pagelimit < 0) {
diff --git a/mod/glossary/showentry.php b/mod/glossary/showentry.php
index daaca7f45bb19..d9218c2f16231 100644
--- a/mod/glossary/showentry.php
+++ b/mod/glossary/showentry.php
@@ -36,7 +36,7 @@
     $entries = glossary_get_entries_search($concept, $courseid);
 
 } else {
-    print_error('invalidelementid');
+    throw new \moodle_exception('invalidelementid');
 }
 
 $PAGE->set_pagelayout('incourse');
diff --git a/mod/glossary/showentry_ajax.php b/mod/glossary/showentry_ajax.php
index 204d76606f529..df7cf58ce8516 100644
--- a/mod/glossary/showentry_ajax.php
+++ b/mod/glossary/showentry_ajax.php
@@ -38,7 +38,7 @@
     $entries = glossary_get_entries_search($concept, $courseid);
 
 } else {
-    print_error('invalidelementid');
+    throw new \moodle_exception('invalidelementid');
 }
 
 if ($entries) {
diff --git a/mod/glossary/view.php b/mod/glossary/view.php
index e22ef571cacaf..6160f954e4e6b 100644
--- a/mod/glossary/view.php
+++ b/mod/glossary/view.php
@@ -23,28 +23,28 @@
 
 if (!empty($id)) {
     if (! $cm = get_coursemodule_from_id('glossary', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $glossary = $DB->get_record("glossary", array("id"=>$cm->instance))) {
-        print_error('invalidid', 'glossary');
+        throw new \moodle_exception('invalidid', 'glossary');
     }
 
 } else if (!empty($g)) {
     if (! $glossary = $DB->get_record("glossary", array("id"=>$g))) {
-        print_error('invalidid', 'glossary');
+        throw new \moodle_exception('invalidid', 'glossary');
     }
     if (! $course = $DB->get_record("course", array("id"=>$glossary->course))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     if (!$cm = get_coursemodule_from_instance("glossary", $glossary->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     $id = $cm->id;
 } else {
-    print_error('invalidid', 'glossary');
+    throw new \moodle_exception('invalidid', 'glossary');
 }
 $cm = cm_info::create($cm);
 
diff --git a/mod/h5pactivity/report.php b/mod/h5pactivity/report.php
index 90837f8846a04..802edf3a40855 100644
--- a/mod/h5pactivity/report.php
+++ b/mod/h5pactivity/report.php
@@ -47,7 +47,7 @@
 
 $report = $manager->get_report($userid, $attemptid);
 if (!$report) {
-    print_error('permissiondenied');
+    throw new \moodle_exception('permissiondenied');
 }
 
 $user = $report->get_user();
diff --git a/mod/label/view.php b/mod/label/view.php
index 3ef5660bba523..193a7959bb17d 100644
--- a/mod/label/view.php
+++ b/mod/label/view.php
@@ -31,27 +31,27 @@
 if ($id) {
     $PAGE->set_url('/mod/label/index.php', array('id'=>$id));
     if (! $cm = get_coursemodule_from_id('label', $id, 0, true)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
 
     if (! $label = $DB->get_record("label", array("id"=>$cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
 } else {
     $PAGE->set_url('/mod/label/index.php', array('l'=>$l));
     if (! $label = $DB->get_record("label", array("id"=>$l))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id"=>$label->course)) ){
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance("label", $label->id, $course->id, true)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
diff --git a/mod/lesson/essay.php b/mod/lesson/essay.php
index f70a42f4b1745..f50a52696ca7e 100644
--- a/mod/lesson/essay.php
+++ b/mod/lesson/essay.php
@@ -84,13 +84,13 @@
         require_sesskey();
 
         if (empty($attempt)) {
-            print_error('cannotfindattempt', 'lesson');
+            throw new \moodle_exception('cannotfindattempt', 'lesson');
         }
         if (empty($user)) {
-            print_error('cannotfinduser', 'lesson');
+            throw new \moodle_exception('cannotfinduser', 'lesson');
         }
         if (empty($answer)) {
-            print_error('cannotfindanswer', 'lesson');
+            throw new \moodle_exception('cannotfindanswer', 'lesson');
         }
         break;
 
@@ -98,10 +98,10 @@
         require_sesskey();
 
         if (empty($attempt)) {
-            print_error('cannotfindattempt', 'lesson');
+            throw new \moodle_exception('cannotfindattempt', 'lesson');
         }
         if (empty($user)) {
-            print_error('cannotfinduser', 'lesson');
+            throw new \moodle_exception('cannotfinduser', 'lesson');
         }
 
         $editoroptions = array('noclean' => true, 'maxfiles' => EDITOR_UNLIMITED_FILES,
@@ -116,7 +116,7 @@
         }
         if ($form = $mform->get_data()) {
             if (!$grades = $DB->get_records('lesson_grades', array("lessonid"=>$lesson->id, "userid"=>$attempt->userid), 'completed', '*', $attempt->retry, 1)) {
-                print_error('cannotfindgrade', 'lesson');
+                throw new \moodle_exception('cannotfindgrade', 'lesson');
             }
 
             $essayinfo->graded = 1;
@@ -167,7 +167,7 @@
 
             redirect(new moodle_url('/mod/lesson/essay.php', array('id'=>$cm->id)));
         } else {
-            print_error('invalidformdata');
+            throw new \moodle_exception('invalidformdata');
         }
         break;
     case 'email':
@@ -178,7 +178,7 @@
         if ($userid = optional_param('userid', 0, PARAM_INT)) {
             $queryadd = " AND userid = ?";
             if (! $users = $DB->get_records('user', array('id' => $userid))) {
-                print_error('cannotfinduser', 'lesson');
+                throw new \moodle_exception('cannotfinduser', 'lesson');
             }
         } else {
             $queryadd = '';
@@ -199,7 +199,7 @@
                        ) ui ON u.id = ui.userid
                   JOIN ($esql) ue ON ue.id = u.id
                   ORDER BY $sort", $params)) {
-                print_error('cannotfinduser', 'lesson');
+                throw new \moodle_exception('cannotfinduser', 'lesson');
             }
         }
 
@@ -216,13 +216,13 @@
             $params[] = $userid;
         }
         if (!$attempts = $DB->get_records_select('lesson_attempts', "pageid $usql".$queryadd, $params)) {
-            print_error('nooneansweredthisquestion', 'lesson');
+            throw new \moodle_exception('nooneansweredthisquestion', 'lesson');
         }
         // Get the answers
         list($answerUsql, $parameters) = $DB->get_in_or_equal(array_keys($pages));
         array_unshift($parameters, $lesson->id);
         if (!$answers = $DB->get_records_select('lesson_answers', "lessonid = ? AND pageid $answerUsql", $parameters, '', 'pageid, score')) {
-            print_error('cannotfindanswer', 'lesson');
+            throw new \moodle_exception('cannotfindanswer', 'lesson');
         }
 
         $userpicture = new user_picture($USER);
diff --git a/mod/lesson/format.php b/mod/lesson/format.php
index d7c68d695c14e..4cb3bc5f7c2d3 100644
--- a/mod/lesson/format.php
+++ b/mod/lesson/format.php
@@ -476,7 +476,7 @@ function importprocess($filename, $lesson, $pageid) {
                     if ($pageid) {
                         // the new page follows on from this page
                         if (!$page = $DB->get_record("lesson_pages", array("id" => $pageid))) {
-                            print_error('invalidpageid', 'lesson');
+                            throw new \moodle_exception('invalidpageid', 'lesson');
                         }
                         $newpage->prevpageid = $pageid;
                         $newpage->nextpageid = $page->nextpageid;
diff --git a/mod/lesson/import.php b/mod/lesson/import.php
index 128a6d71e0f45..2e00a64ca6a32 100644
--- a/mod/lesson/import.php
+++ b/mod/lesson/import.php
@@ -78,8 +78,8 @@
     $formatclass = 'qformat_'.$data->format;
     $formatclassfile = $CFG->dirroot.'/question/format/'.$data->format.'/format.php';
     if (!is_readable($formatclassfile)) {
-        print_error('unknowformat','', '', $data->format);
-            }
+        throw new \moodle_exception('unknowformat', '', '', $data->format);
+    }
     require_once($formatclassfile);
     $format = new $formatclass();
 
@@ -87,17 +87,17 @@
 
     // Do anything before that we need to
     if (! $format->importpreprocess()) {
-                print_error('preprocesserror', 'lesson');
+                throw new \moodle_exception('preprocesserror', 'lesson');
             }
 
     // Process the uploaded file
     if (! $format->importprocess($importfile, $lesson, $pageid)) {
-                print_error('processerror', 'lesson');
+                throw new \moodle_exception('processerror', 'lesson');
             }
 
     // In case anything needs to be done after
     if (! $format->importpostprocess()) {
-                print_error('postprocesserror', 'lesson');
+                throw new \moodle_exception('postprocesserror', 'lesson');
             }
 
             echo "<hr>";
diff --git a/mod/lesson/index.php b/mod/lesson/index.php
index 6b425ecb8b2be..3da15f96df30a 100644
--- a/mod/lesson/index.php
+++ b/mod/lesson/index.php
@@ -32,7 +32,7 @@
 $PAGE->set_url('/mod/lesson/index.php', array('id'=>$id));
 
 if (!$course = $DB->get_record("course", array("id" => $id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
diff --git a/mod/lesson/lesson.php b/mod/lesson/lesson.php
index 4256d3994ada7..74baa8c70a9f1 100644
--- a/mod/lesson/lesson.php
+++ b/mod/lesson/lesson.php
@@ -67,7 +67,7 @@
             echo "<p align=\"center\">\n";
             foreach ($answers as $answer) {
                 if (!$title = $DB->get_field("lesson_pages", "title", array("id" => $answer->pageid))) {
-                    print_error('cannotfindpagetitle', 'lesson');
+                    throw new \moodle_exception('cannotfindpagetitle', 'lesson');
                 }
                 echo $title."<br />\n";
             }
@@ -85,7 +85,7 @@
 
         $params = array ("lessonid" => $lesson->id, "prevpageid" => 0);
         if (!$page = $DB->get_record_select("lesson_pages", "lessonid = :lessonid AND prevpageid = :prevpageid", $params)) {
-            print_error('cannotfindfirstpage', 'lesson');
+            throw new \moodle_exception('cannotfindfirstpage', 'lesson');
         }
 
         echo html_writer::start_tag('div', array('class' => 'move-page'));
@@ -109,7 +109,7 @@
             }
             if ($page->nextpageid) {
                 if (!$page = $DB->get_record("lesson_pages", array("id" => $page->nextpageid))) {
-                    print_error('cannotfindnextpage', 'lesson');
+                    throw new \moodle_exception('cannotfindnextpage', 'lesson');
                 }
             } else {
                 // last page reached
@@ -135,7 +135,7 @@
             redirect(new moodle_url('/mod/lesson/edit.php', array('id' => $cm->id)));
         break;
     default:
-        print_error('unknowaction');
+        throw new \moodle_exception('unknowaction');
         break;
 }
 
diff --git a/mod/lesson/locallib.php b/mod/lesson/locallib.php
index 3088327af4278..8d50af0f459ba 100644
--- a/mod/lesson/locallib.php
+++ b/mod/lesson/locallib.php
@@ -183,7 +183,7 @@ function lesson_unseen_branch_jump($lesson, $userid) {
     }
 
     if (!$seenbranches = $lesson->get_content_pages_viewed($retakes, $userid, 'timeseen DESC')) {
-        print_error('cannotfindrecords', 'lesson');
+        throw new \moodle_exception('cannotfindrecords', 'lesson');
     }
 
     // get the lesson pages
@@ -237,7 +237,7 @@ function lesson_random_question_jump($lesson, $pageid) {
     // get the lesson pages
     $params = array ("lessonid" => $lesson->id);
     if (!$lessonpages = $DB->get_records_select("lesson_pages", "lessonid = :lessonid", $params)) {
-        print_error('cannotfindpages', 'lesson');
+        throw new \moodle_exception('cannotfindpages', 'lesson');
     }
 
     // go up the pages till branch table
@@ -584,7 +584,7 @@ function lesson_add_header_buttons($cm, $context, $extraeditbuttons=false, $less
 
     if (has_capability('mod/lesson:edit', $context) && $extraeditbuttons) {
         if ($lessonpageid === null) {
-            print_error('invalidpageid', 'lesson');
+            throw new \moodle_exception('invalidpageid', 'lesson');
         }
         if (!empty($lessonpageid) && $lessonpageid != LESSON_EOL) {
             $url = new moodle_url('/mod/lesson/editpage.php', array(
@@ -1682,7 +1682,7 @@ public static function load($lessonid) {
         global $DB;
 
         if (!$lesson = $DB->get_record('lesson', array('id' => $lessonid))) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
         return new lesson($lesson);
     }
@@ -2068,7 +2068,7 @@ protected function get_firstpageid() {
             if (!$this->loadedallpages) {
                 $firstpageid = $DB->get_field('lesson_pages', 'id', array('lessonid'=>$this->properties->id, 'prevpageid'=>0));
                 if (!$firstpageid) {
-                    print_error('cannotfindfirstpage', 'lesson');
+                    throw new \moodle_exception('cannotfindfirstpage', 'lesson');
                 }
                 $this->firstpageid = $firstpageid;
             } else {
@@ -2089,7 +2089,7 @@ public function get_lastpageid() {
             if (!$this->loadedallpages) {
                 $lastpageid = $DB->get_field('lesson_pages', 'id', array('lessonid'=>$this->properties->id, 'nextpageid'=>0));
                 if (!$lastpageid) {
-                    print_error('cannotfindlastpage', 'lesson');
+                    throw new \moodle_exception('cannotfindlastpage', 'lesson');
                 }
                 $this->lastpageid = $lastpageid;
             } else {
@@ -2718,7 +2718,7 @@ public function resort_pages($pageid, $after) {
         $pages = $this->load_all_pages();
 
         if (!array_key_exists($pageid, $pages) || ($after!=0 && !array_key_exists($after, $pages))) {
-            print_error('cannotfindpages', 'lesson', "$CFG->wwwroot/mod/lesson/edit.php?id=$cm->id");
+            throw new \moodle_exception('cannotfindpages', 'lesson', "$CFG->wwwroot/mod/lesson/edit.php?id=$cm->id");
         }
 
         $pagetomove = clone($pages[$pageid]);
@@ -3920,7 +3920,7 @@ final public static function create($properties, lesson $lesson, $context, $maxb
         if ($properties->pageid) {
             $prevpage = $DB->get_record("lesson_pages", array("id" => $properties->pageid), 'id, nextpageid');
             if (!$prevpage) {
-                print_error('cannotfindpages', 'lesson');
+                throw new \moodle_exception('cannotfindpages', 'lesson');
             }
             $newpage->prevpageid = $prevpage->id;
             $newpage->nextpageid = $prevpage->nextpageid;
@@ -3987,7 +3987,7 @@ final public static function load($id, lesson $lesson) {
         } else {
             $page = $DB->get_record("lesson_pages", array("id" => $id));
             if (!$page) {
-                print_error('cannotfindpages', 'lesson');
+                throw new \moodle_exception('cannotfindpages', 'lesson');
             }
         }
         $manager = lesson_page_type_manager::get($lesson);
@@ -5234,7 +5234,7 @@ public function get_page_type_idstring($id) {
     public function load_page($pageid, lesson $lesson) {
         global $DB;
         if (!($page =$DB->get_record('lesson_pages', array('id'=>$pageid, 'lessonid'=>$lesson->id)))) {
-            print_error('cannotfindpages', 'lesson');
+            throw new \moodle_exception('cannotfindpages', 'lesson');
         }
         $pagetype = get_class($this->types[$page->qtype]);
         $page = new $pagetype($page, $lesson);
diff --git a/mod/lesson/override_form.php b/mod/lesson/override_form.php
index 8bc99865b7d35..e6077182d9ee1 100644
--- a/mod/lesson/override_form.php
+++ b/mod/lesson/override_form.php
@@ -107,7 +107,7 @@ protected function definition() {
                 if (empty($groups)) {
                     // Generate an error.
                     $link = new moodle_url('/mod/lesson/overrides.php', array('cmid' => $cm->id));
-                    print_error('groupsnone', 'lesson', $link);
+                    throw new \moodle_exception('groupsnone', 'lesson', $link);
                 }
 
                 $groupchoices = array();
@@ -166,7 +166,7 @@ protected function definition() {
                 if (empty($users)) {
                     // Generate an error.
                     $link = new moodle_url('/mod/lesson/overrides.php', array('cmid' => $cm->id));
-                    print_error('usersnone', 'lesson', $link);
+                    throw new \moodle_exception('usersnone', 'lesson', $link);
                 }
 
                 $userchoices = array();
diff --git a/mod/lesson/overridedelete.php b/mod/lesson/overridedelete.php
index c17b37ea54a30..ac552ca5b022e 100644
--- a/mod/lesson/overridedelete.php
+++ b/mod/lesson/overridedelete.php
@@ -32,13 +32,13 @@
 $confirm = optional_param('confirm', false, PARAM_BOOL);
 
 if (! $override = $DB->get_record('lesson_overrides', array('id' => $overrideid))) {
-    print_error('invalidoverrideid', 'lesson');
+    throw new \moodle_exception('invalidoverrideid', 'lesson');
 }
 
 $lesson = new lesson($DB->get_record('lesson', array('id' => $override->lessonid), '*', MUST_EXIST));
 
 if (! $cm = get_coursemodule_from_instance("lesson", $lesson->id, $lesson->course)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 
@@ -51,11 +51,11 @@
 
 if ($override->groupid) {
     if (!groups_group_visible($override->groupid, $course, $cm)) {
-        print_error('invalidoverrideid', 'lesson');
+        throw new \moodle_exception('invalidoverrideid', 'lesson');
     }
 } else {
     if (!groups_user_groups_visible($course, $override->userid, $cm)) {
-        print_error('invalidoverrideid', 'lesson');
+        throw new \moodle_exception('invalidoverrideid', 'lesson');
     }
 }
 
diff --git a/mod/lesson/overrideedit.php b/mod/lesson/overrideedit.php
index 8eb60cb51b38e..fc8ae373c6e82 100644
--- a/mod/lesson/overrideedit.php
+++ b/mod/lesson/overrideedit.php
@@ -38,7 +38,7 @@
 if ($overrideid) {
 
     if (! $override = $DB->get_record('lesson_overrides', array('id' => $overrideid))) {
-        print_error('invalidoverrideid', 'lesson');
+        throw new \moodle_exception('invalidoverrideid', 'lesson');
     }
 
     $lesson = new lesson($DB->get_record('lesson', array('id' => $override->lessonid), '*',  MUST_EXIST));
@@ -50,7 +50,7 @@
     $lesson = new lesson($DB->get_record('lesson', array('id' => $cm->instance), '*', MUST_EXIST));
 
 } else {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 
@@ -79,11 +79,11 @@
 
     if ($override->groupid) {
         if (!groups_group_visible($override->groupid, $course, $cm)) {
-            print_error('invalidoverrideid', 'lesson');
+            throw new \moodle_exception('invalidoverrideid', 'lesson');
         }
     } else {
         if (!groups_user_groups_visible($course, $override->userid, $cm)) {
-            print_error('invalidoverrideid', 'lesson');
+            throw new \moodle_exception('invalidoverrideid', 'lesson');
         }
     }
 } else {
diff --git a/mod/lesson/pagetypes/branchtable.php b/mod/lesson/pagetypes/branchtable.php
index 983806989447b..148d25e0e05c6 100644
--- a/mod/lesson/pagetypes/branchtable.php
+++ b/mod/lesson/pagetypes/branchtable.php
@@ -84,7 +84,7 @@ public static function get_jumptooptions($firstpage, lesson $lesson) {
 
         if (!$firstpage) {
             if (!$apageid = $DB->get_field("lesson_pages", "id", array("lessonid" => $lesson->id, "prevpageid" => 0))) {
-                print_error('cannotfindfirstpage', 'lesson');
+                throw new \moodle_exception('cannotfindfirstpage', 'lesson');
             }
             while (true) {
                 if ($apageid) {
diff --git a/mod/lesson/pagetypes/cluster.php b/mod/lesson/pagetypes/cluster.php
index c093c07f912fa..164a1ad1af297 100644
--- a/mod/lesson/pagetypes/cluster.php
+++ b/mod/lesson/pagetypes/cluster.php
@@ -132,7 +132,7 @@ public function construction_override($pageid, lesson $lesson) {
         if ($pageid == 0) {
             if ($lesson->has_pages()) {
                 if (!$page = $DB->get_record("lesson_pages", array("prevpageid" => 0, "lessonid" => $lesson->id))) {
-                    print_error('cannotfindpagerecord', 'lesson');
+                    throw new \moodle_exception('cannotfindpagerecord', 'lesson');
                 }
             } else {
                 // This is the ONLY page
@@ -141,7 +141,7 @@ public function construction_override($pageid, lesson $lesson) {
             }
         } else {
             if (!$page = $DB->get_record("lesson_pages", array("id" => $pageid))) {
-                print_error('cannotfindpagerecord', 'lesson');
+                throw new \moodle_exception('cannotfindpagerecord', 'lesson');
             }
         }
         $newpage = new stdClass;
diff --git a/mod/lesson/pagetypes/endofbranch.php b/mod/lesson/pagetypes/endofbranch.php
index 568f58a142167..fa17245017563 100644
--- a/mod/lesson/pagetypes/endofbranch.php
+++ b/mod/lesson/pagetypes/endofbranch.php
@@ -160,7 +160,7 @@ public function construction_override($pageid, lesson $lesson) {
 
         // the new page is not the first page (end of branch always comes after an existing page)
         if (!$page = $DB->get_record("lesson_pages", array("id" => $pageid))) {
-            print_error('cannotfindpagerecord', 'lesson');
+            throw new \moodle_exception('cannotfindpagerecord', 'lesson');
         }
         // chain back up to find the (nearest branch table)
         $btpage = clone($page);
@@ -168,7 +168,7 @@ public function construction_override($pageid, lesson $lesson) {
         while (($btpage->qtype != LESSON_PAGE_BRANCHTABLE) && ($btpage->prevpageid > 0)) {
             $btpageid = $btpage->prevpageid;
             if (!$btpage = $DB->get_record("lesson_pages", array("id" => $btpageid))) {
-                print_error('cannotfindpagerecord', 'lesson');
+                throw new \moodle_exception('cannotfindpagerecord', 'lesson');
             }
         }
 
diff --git a/mod/lesson/pagetypes/endofcluster.php b/mod/lesson/pagetypes/endofcluster.php
index 207297a835c91..4b756df61ed10 100644
--- a/mod/lesson/pagetypes/endofcluster.php
+++ b/mod/lesson/pagetypes/endofcluster.php
@@ -138,7 +138,7 @@ public function construction_override($pageid, lesson $lesson) {
 
         // the new page is not the first page (end of cluster always comes after an existing page)
         if (!$page = $DB->get_record("lesson_pages", array("id" => $pageid))) {
-            print_error('cannotfindpages', 'lesson');
+            throw new \moodle_exception('cannotfindpages', 'lesson');
         }
 
         // could put code in here to check if the user really can insert an end of cluster
diff --git a/mod/lesson/pagetypes/multichoice.php b/mod/lesson/pagetypes/multichoice.php
index 0415d705aefe3..70e938f315d5d 100644
--- a/mod/lesson/pagetypes/multichoice.php
+++ b/mod/lesson/pagetypes/multichoice.php
@@ -238,7 +238,7 @@ public function check_answer() {
             }
             $result->answerid = $data->answerid;
             if (!$answer = $DB->get_record("lesson_answers", array("id" => $result->answerid))) {
-                print_error("Continue: answer record not found");
+                throw new \moodle_exception("Continue: answer record not found");
             }
             $answer = parent::rewrite_answers_urls($answer);
             if ($this->lesson->jumpto_is_correct($this->properties->id, $answer->jumpto)) {
diff --git a/mod/lesson/report.php b/mod/lesson/report.php
index 789662ff37a69..4d13732ff4b4b 100644
--- a/mod/lesson/report.php
+++ b/mod/lesson/report.php
@@ -366,7 +366,7 @@
         echo html_writer::table($table);
     }
 } else {
-    print_error('unknowaction');
+    throw new \moodle_exception('unknowaction');
 }
 
 /// Finish the page
diff --git a/mod/lesson/tabs.php b/mod/lesson/tabs.php
index e3b385746ff42..94afe5ac558c2 100644
--- a/mod/lesson/tabs.php
+++ b/mod/lesson/tabs.php
@@ -30,7 +30,7 @@
 /// This file to be included so we can assume config.php has already been included.
 global $DB;
 if (empty($lesson)) {
-    print_error('cannotcallscript');
+    throw new \moodle_exception('cannotcallscript');
 }
 if (!isset($currenttab)) {
     $currenttab = '';
diff --git a/mod/page/view.php b/mod/page/view.php
index fc0e7e1c0d593..3215f7468d0c0 100644
--- a/mod/page/view.php
+++ b/mod/page/view.php
@@ -34,13 +34,13 @@
 
 if ($p) {
     if (!$page = $DB->get_record('page', array('id'=>$p))) {
-        print_error('invalidaccessparameter');
+        throw new \moodle_exception('invalidaccessparameter');
     }
     $cm = get_coursemodule_from_instance('page', $page->id, $page->course, false, MUST_EXIST);
 
 } else {
     if (!$cm = get_coursemodule_from_id('page', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     $page = $DB->get_record('page', array('id'=>$cm->instance), '*', MUST_EXIST);
 }
diff --git a/mod/quiz/addrandom.php b/mod/quiz/addrandom.php
index 5a20d24d9eb5c..3839ca47c068f 100644
--- a/mod/quiz/addrandom.php
+++ b/mod/quiz/addrandom.php
@@ -43,13 +43,13 @@
 
 // Get the course object and related bits.
 if (!$course = $DB->get_record('course', array('id' => $quiz->course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 // You need mod/quiz:manage in addition to question capabilities to access this page.
 // You also need the moodle/question:useall capability somewhere.
 require_capability('mod/quiz:manage', $contexts->lowest());
 if (!$contexts->having_cap('moodle/question:useall')) {
-    print_error('nopermissions', '', '', 'use');
+    throw new \moodle_exception('nopermissions', '', '', 'use');
 }
 
 $PAGE->set_url($thispageurl);
@@ -132,7 +132,7 @@
 echo $OUTPUT->header();
 
 if (!$quizname = $DB->get_field($cm->modname, 'name', array('id' => $cm->instance))) {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
 }
 
 echo $OUTPUT->heading(get_string('addrandomquestiontoquiz', 'quiz', $quizname), 2);
diff --git a/mod/quiz/attempt.php b/mod/quiz/attempt.php
index 659f6d2a2a2d1..ecd85256505a4 100644
--- a/mod/quiz/attempt.php
+++ b/mod/quiz/attempt.php
@@ -30,7 +30,7 @@
     redirect($CFG->wwwroot . '/mod/quiz/startattempt.php?cmid=' . $id . '&sesskey=' . sesskey());
 } else if ($qid = optional_param('q', 0, PARAM_INT)) {
     if (!$cm = get_coursemodule_from_instance('quiz', $qid)) {
-        print_error('invalidquizid', 'quiz');
+        throw new \moodle_exception('invalidquizid', 'quiz');
     }
     redirect(new moodle_url('/mod/quiz/startattempt.php',
             array('cmid' => $cm->id, 'sesskey' => sesskey())));
@@ -85,7 +85,7 @@
 $output = $PAGE->get_renderer('mod_quiz');
 $messages = $accessmanager->prevent_access();
 if (!$attemptobj->is_preview_user() && $messages) {
-    print_error('attempterror', 'quiz', $attemptobj->view_url(),
+    throw new \moodle_exception('attempterror', 'quiz', $attemptobj->view_url(),
             $output->access_messages($messages));
 }
 if ($accessmanager->is_preflight_check_required($attemptobj->get_attemptid())) {
diff --git a/mod/quiz/comment.php b/mod/quiz/comment.php
index 9d55b4092bcbf..6a8ef3a355d82 100644
--- a/mod/quiz/comment.php
+++ b/mod/quiz/comment.php
@@ -38,7 +38,7 @@
 
 // Can only grade finished attempts.
 if (!$attemptobj->is_finished()) {
-    print_error('attemptclosed', 'quiz');
+    throw new \moodle_exception('attemptclosed', 'quiz');
 }
 
 // Check login and permissions.
diff --git a/mod/quiz/index.php b/mod/quiz/index.php
index 6c87002f62c91..ec7fb984ce98d 100644
--- a/mod/quiz/index.php
+++ b/mod/quiz/index.php
@@ -29,7 +29,7 @@
 $id = required_param('id', PARAM_INT);
 $PAGE->set_url('/mod/quiz/index.php', array('id'=>$id));
 if (!$course = $DB->get_record('course', array('id' => $id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 $coursecontext = context_course::instance($id);
 require_login($course);
diff --git a/mod/quiz/locallib.php b/mod/quiz/locallib.php
index b3f6de1720a67..2cc66d3bfdb56 100644
--- a/mod/quiz/locallib.php
+++ b/mod/quiz/locallib.php
@@ -113,7 +113,7 @@ function quiz_create_attempt(quiz $quizobj, $attemptnumber, $lastattempt, $timen
     } else {
         // Build on last attempt.
         if (empty($lastattempt)) {
-            print_error('cannotfindprevattempt', 'quiz');
+            throw new \moodle_exception('cannotfindprevattempt', 'quiz');
         }
         $attempt = $lastattempt;
     }
diff --git a/mod/quiz/override_form.php b/mod/quiz/override_form.php
index 164e108204379..c44a4da696de7 100644
--- a/mod/quiz/override_form.php
+++ b/mod/quiz/override_form.php
@@ -103,7 +103,7 @@ protected function definition() {
                 if (empty($groups)) {
                     // Generate an error.
                     $link = new moodle_url('/mod/quiz/overrides.php', array('cmid'=>$cm->id));
-                    print_error('groupsnone', 'quiz', $link);
+                    throw new \moodle_exception('groupsnone', 'quiz', $link);
                 }
 
                 $groupchoices = array();
@@ -180,7 +180,7 @@ protected function definition() {
                 if (empty($users)) {
                     // Generate an error.
                     $link = new moodle_url('/mod/quiz/overrides.php', array('cmid'=>$cm->id));
-                    print_error('usersnone', 'quiz', $link);
+                    throw new \moodle_exception('usersnone', 'quiz', $link);
                 }
 
                 $userchoices = [];
diff --git a/mod/quiz/overridedelete.php b/mod/quiz/overridedelete.php
index 258973a5ad5a3..117ab70fafc64 100644
--- a/mod/quiz/overridedelete.php
+++ b/mod/quiz/overridedelete.php
@@ -32,13 +32,13 @@
 $confirm = optional_param('confirm', false, PARAM_BOOL);
 
 if (! $override = $DB->get_record('quiz_overrides', array('id' => $overrideid))) {
-    print_error('invalidoverrideid', 'quiz');
+    throw new \moodle_exception('invalidoverrideid', 'quiz');
 }
 if (! $quiz = $DB->get_record('quiz', array('id' => $override->quiz))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 if (! $cm = get_coursemodule_from_instance("quiz", $quiz->id, $quiz->course)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id'=>$cm->course), '*', MUST_EXIST);
 
@@ -51,11 +51,11 @@
 
 if ($override->groupid) {
     if (!groups_group_visible($override->groupid, $course, $cm)) {
-        print_error('invalidoverrideid', 'quiz');
+        throw new \moodle_exception('invalidoverrideid', 'quiz');
     }
 } else {
     if (!groups_user_groups_visible($course, $override->userid, $cm)) {
-        print_error('invalidoverrideid', 'quiz');
+        throw new \moodle_exception('invalidoverrideid', 'quiz');
     }
 }
 
diff --git a/mod/quiz/overrideedit.php b/mod/quiz/overrideedit.php
index 93cd3c2f13e4d..3450be23ee58a 100644
--- a/mod/quiz/overrideedit.php
+++ b/mod/quiz/overrideedit.php
@@ -38,10 +38,10 @@
 if ($overrideid) {
 
     if (! $override = $DB->get_record('quiz_overrides', array('id' => $overrideid))) {
-        print_error('invalidoverrideid', 'quiz');
+        throw new \moodle_exception('invalidoverrideid', 'quiz');
     }
     if (! $quiz = $DB->get_record('quiz', array('id' => $override->quiz))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     list($course, $cm) = get_course_and_cm_from_instance($quiz, 'quiz');
 
@@ -50,7 +50,7 @@
     $quiz = $DB->get_record('quiz', array('id' => $cm->instance), '*', MUST_EXIST);
 
 } else {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id'=>$cm->course), '*', MUST_EXIST);
 
@@ -82,11 +82,11 @@
 
     if ($override->groupid) {
         if (!groups_group_visible($override->groupid, $course, $cm)) {
-            print_error('invalidoverrideid', 'quiz');
+            throw new \moodle_exception('invalidoverrideid', 'quiz');
         }
     } else {
         if (!groups_user_groups_visible($course, $override->userid, $cm)) {
-            print_error('invalidoverrideid', 'quiz');
+            throw new \moodle_exception('invalidoverrideid', 'quiz');
         }
     }
 } else {
diff --git a/mod/quiz/report.php b/mod/quiz/report.php
index d3e788c8b9c93..7b38f6f0ef944 100644
--- a/mod/quiz/report.php
+++ b/mod/quiz/report.php
@@ -35,24 +35,24 @@
 
 if ($id) {
     if (!$cm = get_coursemodule_from_id('quiz', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (!$course = $DB->get_record('course', array('id' => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (!$quiz = $DB->get_record('quiz', array('id' => $cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
 } else {
     if (!$quiz = $DB->get_record('quiz', array('id' => $q))) {
-        print_error('invalidquizid', 'quiz');
+        throw new \moodle_exception('invalidquizid', 'quiz');
     }
     if (!$course = $DB->get_record('course', array('id' => $quiz->course))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     if (!$cm = get_coursemodule_from_instance("quiz", $quiz->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
@@ -68,7 +68,7 @@
 $PAGE->activityheader->disable();
 $reportlist = quiz_report_list($context);
 if (empty($reportlist)) {
-    print_error('erroraccessingreport', 'quiz');
+    throw new \moodle_exception('erroraccessingreport', 'quiz');
 }
 
 // Validate the requested report name.
@@ -77,10 +77,10 @@
     $url->param('mode', reset($reportlist));
     redirect($url);
 } else if (!in_array($mode, $reportlist)) {
-    print_error('erroraccessingreport', 'quiz');
+    throw new \moodle_exception('erroraccessingreport', 'quiz');
 }
 if (!is_readable("report/$mode/report.php")) {
-    print_error('reportnotfound', 'quiz', '', $mode);
+    throw new \moodle_exception('reportnotfound', 'quiz', '', $mode);
 }
 
 // Open the selected quiz report and display it.
@@ -90,7 +90,7 @@
 }
 $reportclassname = 'quiz_' . $mode . '_report';
 if (!class_exists($reportclassname)) {
-    print_error('preprocesserror', 'quiz');
+    throw new \moodle_exception('preprocesserror', 'quiz');
 }
 
 $report = new $reportclassname();
diff --git a/mod/quiz/report/statistics/report.php b/mod/quiz/report/statistics/report.php
index 3492d0ae3b63f..c1bd29dce6ec9 100644
--- a/mod/quiz/report/statistics/report.php
+++ b/mod/quiz/report/statistics/report.php
@@ -202,7 +202,7 @@ public function display($quiz, $cm, $course) {
         } else if ($qid) {
             // Report on an individual sub-question indexed questionid.
             if (!$questionstats->has_subq($qid, $variantno)) {
-                print_error('questiondoesnotexist', 'question');
+                throw new \moodle_exception('questiondoesnotexist', 'question');
             }
 
             $this->output_individual_question_data($quiz, $questionstats->for_subq($qid, $variantno));
@@ -219,7 +219,7 @@ public function display($quiz, $cm, $course) {
         } else if ($slot) {
             // Report on an individual question indexed by position.
             if (!isset($questions[$slot])) {
-                print_error('questiondoesnotexist', 'question');
+                throw new \moodle_exception('questiondoesnotexist', 'question');
             }
 
             if ($variantno === null &&
diff --git a/mod/quiz/startattempt.php b/mod/quiz/startattempt.php
index ed05d61fca305..b71771ab0c8fa 100644
--- a/mod/quiz/startattempt.php
+++ b/mod/quiz/startattempt.php
@@ -35,10 +35,10 @@
 $page = optional_param('page', -1, PARAM_INT); // Page to jump to in the attempt.
 
 if (!$cm = get_coursemodule_from_id('quiz', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 if (!$course = $DB->get_record('course', array('id' => $cm->course))) {
-    print_error("coursemisconf");
+    throw new \moodle_exception("coursemisconf");
 }
 
 $quizobj = quiz::create($cm->instance, $USER->id);
@@ -57,7 +57,7 @@
     if ($quizobj->has_capability('mod/quiz:manage')) {
         redirect($quizobj->edit_url());
     } else {
-        print_error('cannotstartnoquestions', 'quiz', $quizobj->view_url());
+        throw new \moodle_exception('cannotstartnoquestions', 'quiz', $quizobj->view_url());
     }
 }
 
@@ -72,7 +72,7 @@
 // Check access.
 if (!$quizobj->is_preview_user() && $messages) {
     $output = $PAGE->get_renderer('mod_quiz');
-    print_error('attempterror', 'quiz', $quizobj->view_url(),
+    throw new \moodle_exception('attempterror', 'quiz', $quizobj->view_url(),
             $output->access_messages($messages));
 }
 
diff --git a/mod/quiz/summary.php b/mod/quiz/summary.php
index 64186e6428840..496ed8e960caa 100644
--- a/mod/quiz/summary.php
+++ b/mod/quiz/summary.php
@@ -63,7 +63,7 @@
 $output = $PAGE->get_renderer('mod_quiz');
 $messages = $accessmanager->prevent_access();
 if (!$attemptobj->is_preview_user() && $messages) {
-    print_error('attempterror', 'quiz', $attemptobj->view_url(),
+    throw new \moodle_exception('attempterror', 'quiz', $attemptobj->view_url(),
             $output->access_messages($messages));
 }
 if ($accessmanager->is_preflight_check_required($attemptobj->get_attemptid())) {
diff --git a/mod/quiz/view.php b/mod/quiz/view.php
index fd43e720f6395..b08f53d16c678 100644
--- a/mod/quiz/view.php
+++ b/mod/quiz/view.php
@@ -35,20 +35,20 @@
 
 if ($id) {
     if (!$cm = get_coursemodule_from_id('quiz', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (!$course = $DB->get_record('course', array('id' => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
 } else {
     if (!$quiz = $DB->get_record('quiz', array('id' => $q))) {
-        print_error('invalidquizid', 'quiz');
+        throw new \moodle_exception('invalidquizid', 'quiz');
     }
     if (!$course = $DB->get_record('course', array('id' => $quiz->course))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     if (!$cm = get_coursemodule_from_instance("quiz", $quiz->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 }
 
diff --git a/mod/resource/view.php b/mod/resource/view.php
index e351bd2deb8d9..b6edf84ea3c84 100644
--- a/mod/resource/view.php
+++ b/mod/resource/view.php
@@ -36,14 +36,14 @@
 if ($r) {
     if (!$resource = $DB->get_record('resource', array('id'=>$r))) {
         resource_redirect_if_migrated($r, 0);
-        print_error('invalidaccessparameter');
+        throw new \moodle_exception('invalidaccessparameter');
     }
     $cm = get_coursemodule_from_instance('resource', $resource->id, $resource->course, false, MUST_EXIST);
 
 } else {
     if (!$cm = get_coursemodule_from_id('resource', $id)) {
         resource_redirect_if_migrated(0, $id);
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     $resource = $DB->get_record('resource', array('id'=>$cm->instance), '*', MUST_EXIST);
 }
diff --git a/mod/scorm/aicc.php b/mod/scorm/aicc.php
index 8902fd2657705..9598e3f17a616 100644
--- a/mod/scorm/aicc.php
+++ b/mod/scorm/aicc.php
@@ -44,14 +44,14 @@
 if (empty($cfgscorm->allowaicchacp)) {
     require_login();
     if (!confirm_sesskey($sessionid)) {
-        print_error('invalidsesskey');
+        throw new \moodle_exception('invalidsesskey');
     }
     $aiccuser = $USER;
     $scormsession = $SESSION->scorm;
 } else {
     $scormsession = scorm_aicc_confirm_hacp_session($sessionid);
     if (empty($scormsession)) {
-        print_error('invalidhacpsession', 'scorm');
+        throw new \moodle_exception('invalidhacpsession', 'scorm');
     }
     $aiccuser = $DB->get_record('user', array('id' => $scormsession->userid), 'id,username,lastname,firstname', MUST_EXIST);
 }
@@ -62,7 +62,7 @@
     if (isset($scormsession->scoid)) {
         $scoid = $scormsession->scoid;
     } else {
-        print_error('cannotcallscript');
+        throw new \moodle_exception('cannotcallscript');
     }
     $mode = 'normal';
     if (isset($scormsession->scormmode)) {
@@ -80,10 +80,10 @@
 
     if ($sco = scorm_get_sco($scoid, SCO_ONLY)) {
         if (!$scorm = $DB->get_record('scorm', array('id' => $sco->scorm))) {
-            print_error('cannotcallscript');
+            throw new \moodle_exception('cannotcallscript');
         }
     } else {
-        print_error('cannotcallscript');
+        throw new \moodle_exception('cannotcallscript');
     }
     $aiccrequest = "MOODLE scoid: $scoid"
                  . "\r\nMOODLE mode: $mode"
@@ -192,7 +192,7 @@
                         echo 'Max_Time_Allowed='.$userdata->max_time_allowed."\r\n";
                         echo 'Time_Limit_Action='.$userdata->time_limit_action."\r\n";
                     } else {
-                        print_error('cannotfindsco', 'scorm');
+                        throw new \moodle_exception('cannotfindsco', 'scorm');
                     }
                 }
             break;
diff --git a/mod/scorm/datamodel.php b/mod/scorm/datamodel.php
index 612efd0a08247..7dafc71779d1c 100644
--- a/mod/scorm/datamodel.php
+++ b/mod/scorm/datamodel.php
@@ -24,26 +24,26 @@
 
 if (!empty($id)) {
     if (! $cm = get_coursemodule_from_id('scorm', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $scorm = $DB->get_record("scorm", array("id" => $cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else if (!empty($a)) {
     if (! $scorm = $DB->get_record("scorm", array("id" => $a))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $scorm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance("scorm", $scorm->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 $PAGE->set_url('/mod/scorm/datamodel.php', array('scoid' => $scoid, 'attempt' => $attempt, 'id' => $cm->id));
diff --git a/mod/scorm/datamodels/aicclib.php b/mod/scorm/datamodels/aicclib.php
index d06cd5ca4988c..35f1450835f92 100644
--- a/mod/scorm/datamodels/aicclib.php
+++ b/mod/scorm/datamodels/aicclib.php
@@ -520,10 +520,10 @@ function get_scorm_default (&$userdata, $scorm, $scoid, $attempt, $mode) {
             $userdata->$key = $value;
         }
     } else {
-        print_error('cannotfindsco', 'scorm');
+        throw new \moodle_exception('cannotfindsco', 'scorm');
     }
     if (!$sco = scorm_get_sco($scoid)) {
-        print_error('cannotfindsco', 'scorm');
+        throw new \moodle_exception('cannotfindsco', 'scorm');
     }
 
     $userdata->mode = 'normal';
diff --git a/mod/scorm/datamodels/scorm_12lib.php b/mod/scorm/datamodels/scorm_12lib.php
index 79db435f87a18..4857f9921d55f 100644
--- a/mod/scorm/datamodels/scorm_12lib.php
+++ b/mod/scorm/datamodels/scorm_12lib.php
@@ -49,10 +49,10 @@ function get_scorm_default (&$userdata, $scorm, $scoid, $attempt, $mode) {
             $userdata->$key = $value;
         }
     } else {
-        print_error('cannotfindsco', 'scorm');
+        throw new \moodle_exception('cannotfindsco', 'scorm');
     }
     if (!$sco = scorm_get_sco($scoid)) {
-        print_error('cannotfindsco', 'scorm');
+        throw new \moodle_exception('cannotfindsco', 'scorm');
     }
 
     if (isset($userdata->status)) {
diff --git a/mod/scorm/datamodels/scorm_13lib.php b/mod/scorm/datamodels/scorm_13lib.php
index 0048cd49fc5a3..6eb017f68a016 100644
--- a/mod/scorm/datamodels/scorm_13lib.php
+++ b/mod/scorm/datamodels/scorm_13lib.php
@@ -1219,10 +1219,10 @@ function get_scorm_default (&$userdata, $scorm, $scoid, $attempt, $mode) {
             $userdata->$key = $value;
         }
     } else {
-        print_error('cannotfindsco', 'scorm');
+        throw new \moodle_exception('cannotfindsco', 'scorm');
     }
     if (!$sco = scorm_get_sco($scoid)) {
-        print_error('cannotfindsco', 'scorm');
+        throw new \moodle_exception('cannotfindsco', 'scorm');
     }
 
     if (isset($userdata->status)) {
diff --git a/mod/scorm/datamodels/sequencinghandler.php b/mod/scorm/datamodels/sequencinghandler.php
index b041f0e91ad88..ad2602d01d300 100644
--- a/mod/scorm/datamodels/sequencinghandler.php
+++ b/mod/scorm/datamodels/sequencinghandler.php
@@ -33,7 +33,7 @@
     $course = $DB->get_record("course", array("id" => $scorm->course), '*', MUST_EXIST);
     $cm = get_coursemodule_from_instance("scorm", $scorm->id, $course->id, false, MUST_EXIST);
 } else {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 $PAGE->set_url('/mod/scorm/datamodels/sequencinghandler.php',
diff --git a/mod/scorm/deprecatedlib.php b/mod/scorm/deprecatedlib.php
index 3c3246572ee96..f29515abb10be 100644
--- a/mod/scorm/deprecatedlib.php
+++ b/mod/scorm/deprecatedlib.php
@@ -45,7 +45,7 @@ function scorm_get_completion_state($course, $cm, $userid, $type) {
 
     // Get scorm.
     if (!$scorm = $DB->get_record('scorm', array('id' => $cm->instance))) {
-        print_error('cannotfindscorm');
+        throw new \moodle_exception('cannotfindscorm');
     }
     // Only check for existence of tracks and return false if completionstatusrequired or completionscorerequired
     // this means that if only view is required we don't end up with a false state.
diff --git a/mod/scorm/grade.php b/mod/scorm/grade.php
index c611b82f33b72..adefa0aad72bc 100644
--- a/mod/scorm/grade.php
+++ b/mod/scorm/grade.php
@@ -28,15 +28,15 @@
 $id = required_param('id', PARAM_INT); // Course module ID.
 
 if (! $cm = get_coursemodule_from_id('scorm', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $scorm = $DB->get_record('scorm', array('id' => $cm->instance))) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record('course', array('id' => $scorm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 require_login($course, false, $cm);
diff --git a/mod/scorm/index.php b/mod/scorm/index.php
index 45212d342a5a1..95e9f9da295e6 100644
--- a/mod/scorm/index.php
+++ b/mod/scorm/index.php
@@ -23,10 +23,10 @@
 
 if (!empty($id)) {
     if (!$course = $DB->get_record('course', array('id' => $id))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 } else {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 require_course_login($course);
diff --git a/mod/scorm/loadSCO.php b/mod/scorm/loadSCO.php
index 3a590e87e1fa2..9e8fbbbeb1209 100644
--- a/mod/scorm/loadSCO.php
+++ b/mod/scorm/loadSCO.php
@@ -25,26 +25,26 @@
 
 if (!empty($id)) {
     if (! $cm = get_coursemodule_from_id('scorm', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record('course', array('id' => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $scorm = $DB->get_record('scorm', array('id' => $cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else if (!empty($a)) {
     if (! $scorm = $DB->get_record('scorm', array('id' => $a))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $course = $DB->get_record('course', array('id' => $scorm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance('scorm', $scorm->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 $PAGE->set_url('/mod/scorm/loadSCO.php', array('scoid' => $scoid, 'id' => $cm->id));
diff --git a/mod/scorm/player.php b/mod/scorm/player.php
index a4f875031516f..5962d31080722 100644
--- a/mod/scorm/player.php
+++ b/mod/scorm/player.php
@@ -30,26 +30,26 @@
 
 if (!empty($id)) {
     if (! $cm = get_coursemodule_from_id('scorm', $id, 0, true)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $scorm = $DB->get_record("scorm", array("id" => $cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else if (!empty($a)) {
     if (! $scorm = $DB->get_record("scorm", array("id" => $a))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $scorm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance("scorm", $scorm->id, $course->id, true)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 // PARAM_RAW is used for $currentorg, validate it against records stored in the table.
diff --git a/mod/scorm/prereqs.php b/mod/scorm/prereqs.php
index 00a7662daea13..72a8279295095 100644
--- a/mod/scorm/prereqs.php
+++ b/mod/scorm/prereqs.php
@@ -28,26 +28,26 @@
 
 if (!empty($id)) {
     if (! $cm = get_coursemodule_from_id('scorm', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $scorm = $DB->get_record("scorm", array("id" => $cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else if (!empty($a)) {
     if (! $scorm = $DB->get_record("scorm", array("id" => $a))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $scorm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance("scorm", $scorm->id, $course->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 // PARAM_RAW is used for $currentorg, validate it against records stored in the table.
diff --git a/mod/scorm/report.php b/mod/scorm/report.php
index a883fd0b6adfd..527b15cd92950 100644
--- a/mod/scorm/report.php
+++ b/mod/scorm/report.php
@@ -45,7 +45,7 @@
 if (empty($mode)) {
     $mode = reset($reportlist);
 } else if (!in_array($mode, $reportlist)) {
-    print_error('erroraccessingreport', 'scorm');
+    throw new \moodle_exception('erroraccessingreport', 'scorm');
 }
 $url->param('mode', $mode);
 
@@ -60,7 +60,7 @@
 navigation_node::override_active_url(new moodle_url('/mod/scorm/report.php', ['id' => $id]));
 
 if (count($reportlist) < 1) {
-    print_error('erroraccessingreport', 'scorm');
+    throw new \moodle_exception('erroraccessingreport', 'scorm');
 }
 
 // Trigger a report viewed event.
diff --git a/mod/scorm/view.php b/mod/scorm/view.php
index d285c7d1a62bf..d8d24016f876e 100644
--- a/mod/scorm/view.php
+++ b/mod/scorm/view.php
@@ -27,26 +27,26 @@
 
 if (!empty($id)) {
     if (! $cm = get_coursemodule_from_id('scorm', $id, 0, true)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $scorm = $DB->get_record("scorm", array("id" => $cm->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else if (!empty($a)) {
     if (! $scorm = $DB->get_record("scorm", array("id" => $a))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     if (! $course = $DB->get_record("course", array("id" => $scorm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
     if (! $cm = get_coursemodule_from_instance("scorm", $scorm->id, $course->id, true)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 } else {
-    print_error('missingparameter');
+    throw new \moodle_exception('missingparameter');
 }
 
 $url = new moodle_url('/mod/scorm/view.php', array('id' => $cm->id));
diff --git a/mod/survey/download.php b/mod/survey/download.php
index d633cb31ddac2..bf7de9c786c3e 100644
--- a/mod/survey/download.php
+++ b/mod/survey/download.php
@@ -33,11 +33,11 @@
 $group = optional_param('group', 0, PARAM_INT);
 
 if (! $cm = get_coursemodule_from_id('survey', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 $context = context_module::instance($cm->id);
@@ -48,7 +48,7 @@
 require_capability('mod/survey:download', $context) ;
 
 if (! $survey = $DB->get_record("survey", array("id"=>$cm->instance))) {
-    print_error('invalidsurveyid', 'survey');
+    throw new \moodle_exception('invalidsurveyid', 'survey');
 }
 
 $params = array(
@@ -135,7 +135,7 @@
 
 // Get and collate all the results in one big array
 if (! $surveyanswers = $DB->get_records("survey_answers", array("survey"=>$survey->id), "time ASC")) {
-    print_error('cannotfindanswer', 'survey');
+    throw new \moodle_exception('cannotfindanswer', 'survey');
 }
 
 $results = array();
@@ -194,7 +194,7 @@
         $col = 0;
         $row++;
         if (! $u = $DB->get_record("user", array("id"=>$user))) {
-            print_error('invaliduserid');
+            throw new \moodle_exception('invaliduserid');
         }
         if ($n = $DB->get_record("survey_analysis", array("survey"=>$survey->id, "userid"=>$user))) {
             $notes = $n->notes;
@@ -270,7 +270,7 @@
         $col = 0;
         $row++;
         if (! $u = $DB->get_record("user", array("id"=>$user))) {
-            print_error('invaliduserid');
+            throw new \moodle_exception('invaliduserid');
         }
         if ($n = $DB->get_record("survey_analysis", array("survey"=>$survey->id, "userid"=>$user))) {
             $notes = $n->notes;
@@ -336,7 +336,7 @@
 // Print all the lines of data.
 foreach ($results as $user => $rest) {
     if (! $u = $DB->get_record("user", array("id"=>$user))) {
-        print_error('invaliduserid');
+        throw new \moodle_exception('invaliduserid');
     }
     echo $survey->id."\t";
     echo strip_tags(format_string($survey->name,true))."\t";
diff --git a/mod/survey/graph.php b/mod/survey/graph.php
index dc8c88d266671..df7378af78369 100644
--- a/mod/survey/graph.php
+++ b/mod/survey/graph.php
@@ -46,16 +46,16 @@
 $PAGE->set_url($url);
 
 if (!$cm = get_coursemodule_from_id('survey', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 if (!$course = $DB->get_record("course", array("id" => $cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 if ($sid) {
     if (!$user = $DB->get_record("user", array("id" => $sid))) {
-        print_error('invaliduserid');
+        throw new \moodle_exception('invaliduserid');
     }
 }
 
@@ -66,14 +66,14 @@
 
 if (!has_capability('mod/survey:readresponses', $context)) {
     if ($type != "student.png" or $sid != $USER->id) {
-        print_error('nopermissiontoshow');
+        throw new \moodle_exception('nopermissiontoshow');
     } else if ($groupmode and !groups_is_member($group)) {
-        print_error('nopermissiontoshow');
+        throw new \moodle_exception('nopermissiontoshow');
     }
 }
 
 if (!$survey = $DB->get_record("survey", array("id" => $cm->instance))) {
-    print_error('invalidsurveyid', 'survey');
+    throw new \moodle_exception('invalidsurveyid', 'survey');
 }
 
 // Check to see if groups are being used in this survey.
diff --git a/mod/survey/index.php b/mod/survey/index.php
index a3e9f257fcc95..edbdf079d741c 100644
--- a/mod/survey/index.php
+++ b/mod/survey/index.php
@@ -8,7 +8,7 @@
     $PAGE->set_url('/mod/survey/index.php', array('id'=>$id));
 
     if (!$course = $DB->get_record('course', array('id'=>$id))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
     require_course_login($course);
diff --git a/mod/survey/mod_form.php b/mod/survey/mod_form.php
index 385c9dd9343cb..5ba2bf86e9302 100644
--- a/mod/survey/mod_form.php
+++ b/mod/survey/mod_form.php
@@ -26,7 +26,7 @@ function definition() {
         $mform->addRule('name', null, 'required', null, 'client');
 
         if (!$options = $DB->get_records_menu("survey", array("template"=>0), "name", "id, name")) {
-            print_error('cannotfindsurveytmpt', 'survey');
+            throw new \moodle_exception('cannotfindsurveytmpt', 'survey');
         }
 
         foreach ($options as $id => $name) {
diff --git a/mod/survey/report.php b/mod/survey/report.php
index ba01f744d8dcd..f4042cc9a918b 100644
--- a/mod/survey/report.php
+++ b/mod/survey/report.php
@@ -300,7 +300,7 @@
 
     case "question":
         if (!$question = $DB->get_record("survey_questions", array("id" => $qid))) {
-            print_error('cannotfindquestion', 'survey');
+            throw new \moodle_exception('cannotfindquestion', 'survey');
         }
         $question->text = get_string($question->text, "survey");
 
diff --git a/mod/survey/save.php b/mod/survey/save.php
index 5ea69c97b85e6..e721c410b7780 100644
--- a/mod/survey/save.php
+++ b/mod/survey/save.php
@@ -31,17 +31,17 @@
 // Make sure this is a legitimate posting
 
     if (!$formdata = data_submitted() or !confirm_sesskey()) {
-        print_error('cannotcallscript');
+        throw new \moodle_exception('cannotcallscript');
     }
 
     $id = required_param('id', PARAM_INT);    // Course Module ID
 
     if (! $cm = get_coursemodule_from_id('survey', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     if (! $course = $DB->get_record("course", array("id"=>$cm->course))) {
-        print_error('coursemisconf');
+        throw new \moodle_exception('coursemisconf');
     }
 
     $PAGE->set_url('/mod/survey/save.php', array('id'=>$id));
@@ -51,7 +51,7 @@
     require_capability('mod/survey:participate', $context);
 
     if (! $survey = $DB->get_record("survey", array("id"=>$cm->instance))) {
-        print_error('invalidsurveyid', 'survey');
+        throw new \moodle_exception('invalidsurveyid', 'survey');
     }
 
     $strsurveysaved = get_string('surveysaved', 'survey');
diff --git a/mod/survey/view.php b/mod/survey/view.php
index 9a1a70a1bd828..bb16507ac4204 100644
--- a/mod/survey/view.php
+++ b/mod/survey/view.php
@@ -28,13 +28,13 @@
 $id = required_param('id', PARAM_INT);    // Course Module ID.
 
 if (! $cm = get_coursemodule_from_id('survey', $id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $cm = cm_info::create($cm);
 
 if (! $course = $DB->get_record("course", array("id" => $cm->course))) {
-    print_error('coursemisconf');
+    throw new \moodle_exception('coursemisconf');
 }
 
 $PAGE->set_url('/mod/survey/view.php', array('id' => $id));
@@ -44,7 +44,7 @@
 require_capability('mod/survey:participate', $context);
 
 if (! $survey = $DB->get_record("survey", array("id" => $cm->instance))) {
-    print_error('invalidsurveyid', 'survey');
+    throw new \moodle_exception('invalidsurveyid', 'survey');
 }
 $trimmedintro = trim($survey->intro);
 if (empty($trimmedintro)) {
@@ -53,7 +53,7 @@
 }
 
 if (! $template = $DB->get_record("survey", array("id" => $survey->template))) {
-    print_error('invalidtmptid', 'survey');
+    throw new \moodle_exception('invalidtmptid', 'survey');
 }
 
 $showscales = ($template->name != 'ciqname');
diff --git a/mod/wiki/admin.php b/mod/wiki/admin.php
index 1537e01775d07..96fc300c2ea7f 100644
--- a/mod/wiki/admin.php
+++ b/mod/wiki/admin.php
@@ -40,23 +40,23 @@
 $fromversion = optional_param('fromversion', 0, PARAM_INT); // min version to be deleted
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 require_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 $context = context_module::instance($cm->id);
@@ -68,7 +68,7 @@
         // Validate that we are deleting from the same subwiki.
         $deletepage = wiki_get_page($delete);
         if (!$deletepage || $deletepage->subwikiid != $page->subwikiid) {
-            print_error('incorrectsubwikiid', 'wiki');
+            throw new \moodle_exception('incorrectsubwikiid', 'wiki');
         }
     }
     wiki_delete_pages($context, $delete, $page->subwikiid);
@@ -90,7 +90,7 @@
     $totalversionstodelete += 1; //added 1 as toversion should be included
 
     if (($totalversionstodelete >= $versioncount) || ($versioncount <= 1)) {
-        print_error('incorrectdeleteversions', 'wiki');
+        throw new \moodle_exception('incorrectdeleteversions', 'wiki');
     } else {
         $versions = array();
         for ($i = $fromversion; $i <= $toversion; $i++) {
diff --git a/mod/wiki/comments.php b/mod/wiki/comments.php
index 3f3bffcbb3244..665acd6b30cee 100644
--- a/mod/wiki/comments.php
+++ b/mod/wiki/comments.php
@@ -40,19 +40,19 @@
 $pageid = required_param('pageid', PARAM_TEXT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
@@ -60,7 +60,7 @@
 require_course_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 // Trigger comment viewed event.
diff --git a/mod/wiki/create.php b/mod/wiki/create.php
index cdd6489da7249..7042e5503e6a8 100644
--- a/mod/wiki/create.php
+++ b/mod/wiki/create.php
@@ -36,7 +36,7 @@
 // so sesskey must be checked
 if ($action == 'create') {
     if (!confirm_sesskey()) {
-        print_error('invalidsesskey');
+        throw new \moodle_exception('invalidsesskey');
     }
 }
 
@@ -44,20 +44,20 @@
     $subwiki = wiki_get_subwiki($swid);
 
     if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-        print_error('incorrectwikiid', 'wiki');
+        throw new \moodle_exception('incorrectwikiid', 'wiki');
     }
 
 } else {
     $subwiki = wiki_get_subwiki_by_group($wid, $group, $uid);
 
     if (!$wiki = wiki_get_wiki($wid)) {
-        print_error('incorrectwikiid', 'wiki');
+        throw new \moodle_exception('incorrectwikiid', 'wiki');
     }
 
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $groups = new stdClass();
diff --git a/mod/wiki/diff.php b/mod/wiki/diff.php
index 98f5344c742bb..658da192a6b8c 100644
--- a/mod/wiki/diff.php
+++ b/mod/wiki/diff.php
@@ -44,31 +44,31 @@
 $comparewith = required_param('comparewith', PARAM_INT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 
 if ($compare >= $comparewith) {
-    print_error('cannotcomparenewerversion', 'wiki');
+    throw new \moodle_exception('cannotcomparenewerversion', 'wiki');
 }
 
 require_course_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 $wikipage = new page_wiki_diff($wiki, $subwiki, $cm, 'modulepage');
diff --git a/mod/wiki/edit.php b/mod/wiki/edit.php
index 2bf77a85abdeb..8e8429ed14bac 100644
--- a/mod/wiki/edit.php
+++ b/mod/wiki/edit.php
@@ -51,25 +51,25 @@
 }
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 
 if (!empty($section) && !$sectioncontent = wiki_get_section_page($page, $section)) {
-    print_error('invalidsection', 'wiki');
+    throw new \moodle_exception('invalidsection', 'wiki');
 }
 
 require_login($course, true, $cm);
@@ -77,12 +77,12 @@
 $context = context_module::instance($cm->id);
 
 if (!wiki_user_can_edit($subwiki)) {
-    print_error('cannoteditpage', 'wiki');
+    throw new \moodle_exception('cannoteditpage', 'wiki');
 }
 
 if ($option == get_string('save', 'wiki')) {
     if (!confirm_sesskey()) {
-        print_error(get_string('invalidsesskey', 'wiki'));
+        throw new \moodle_exception(get_string('invalidsesskey', 'wiki'));
     }
     $wikipage = new page_wiki_save($wiki, $subwiki, $cm);
     $wikipage->set_page($page);
@@ -91,7 +91,7 @@
 } else {
     if ($option == get_string('preview')) {
         if (!confirm_sesskey()) {
-            print_error(get_string('invalidsesskey', 'wiki'));
+            throw new \moodle_exception(get_string('invalidsesskey', 'wiki'));
         }
         $wikipage = new page_wiki_preview($wiki, $subwiki, $cm, 'modulepage');
         $wikipage->set_page($page);
diff --git a/mod/wiki/editcomments.php b/mod/wiki/editcomments.php
index ebdddb4cbf615..0a87d0d826bf7 100644
--- a/mod/wiki/editcomments.php
+++ b/mod/wiki/editcomments.php
@@ -40,29 +40,29 @@
 $commentid = optional_param('commentid', 0, PARAM_INT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 require_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 $editcomments = new page_wiki_editcomment($wiki, $subwiki, $cm, 'modulepage');
 $comment = new stdClass();
 if ($action == 'edit') {
     if (!$comment = $DB->get_record('comments', array('id' => $commentid))) {
-        print_error('invalidcomment');
+        throw new \moodle_exception('invalidcomment');
     }
 }
 
diff --git a/mod/wiki/files.php b/mod/wiki/files.php
index 68f38f5025e5d..675d59a3604d9 100644
--- a/mod/wiki/files.php
+++ b/mod/wiki/files.php
@@ -34,7 +34,7 @@
 $groupanduser = optional_param('groupanduser', null, PARAM_TEXT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if ($groupanduser) {
@@ -46,7 +46,7 @@
 if ($wid) {
     // in group mode
     if (!$wiki = wiki_get_wiki($wid)) {
-        print_error('incorrectwikiid', 'wiki');
+        throw new \moodle_exception('incorrectwikiid', 'wiki');
     }
     if (!$subwiki = wiki_get_subwiki_by_group($wiki->id, $currentgroup, $userid)) {
         // create subwiki if doesn't exist
@@ -56,18 +56,18 @@
 } else {
     // no group
     if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-        print_error('incorrectsubwikiid', 'wiki');
+        throw new \moodle_exception('incorrectsubwikiid', 'wiki');
     }
 
     // Checking wiki instance of that subwiki
     if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-        print_error('incorrectwikiid', 'wiki');
+        throw new \moodle_exception('incorrectwikiid', 'wiki');
     }
 }
 
 // Checking course module instance
 if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 // Checking course instance
@@ -80,7 +80,7 @@
 require_course_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewfiles', 'wiki');
+    throw new \moodle_exception('cannotviewfiles', 'wiki');
 }
 
 $PAGE->set_title(get_string('wikifiles', 'wiki'));
diff --git a/mod/wiki/filesedit.php b/mod/wiki/filesedit.php
index d2c0f2bd7987e..9e048792b8a22 100644
--- a/mod/wiki/filesedit.php
+++ b/mod/wiki/filesedit.php
@@ -34,17 +34,17 @@
 $returnurl = optional_param('returnurl', '', PARAM_LOCALURL);
 
 if (!$subwiki = wiki_get_subwiki($subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 // Checking wiki instance of that subwiki
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 // Checking course module instance
 if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 // Checking course instance
@@ -55,7 +55,7 @@
 require_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 require_capability('mod/wiki:managefiles', $context);
 
diff --git a/mod/wiki/history.php b/mod/wiki/history.php
index e9a8abaaa7bbc..b74688545a635 100644
--- a/mod/wiki/history.php
+++ b/mod/wiki/history.php
@@ -41,19 +41,19 @@
 $allversion = optional_param('allversion', 0, PARAM_INT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
@@ -61,7 +61,7 @@
 require_course_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 // Trigger history viewed event.
diff --git a/mod/wiki/index.php b/mod/wiki/index.php
index 8654658777fb5..b9039bb8aff0c 100644
--- a/mod/wiki/index.php
+++ b/mod/wiki/index.php
@@ -38,7 +38,7 @@
 $PAGE->set_url('/mod/wiki/index.php', array('id' => $id));
 
 if (!$course = $DB->get_record('course', array('id' => $id))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course, true);
diff --git a/mod/wiki/instancecomments.php b/mod/wiki/instancecomments.php
index 32e99c09ef85d..c3bfce1c1ad5d 100644
--- a/mod/wiki/instancecomments.php
+++ b/mod/wiki/instancecomments.php
@@ -49,25 +49,25 @@
 }
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 require_login($course, true, $cm);
 
 if ($action == 'add' || $action == 'edit') {
     //just check sesskey
     if (!confirm_sesskey()) {
-        print_error(get_string('invalidsesskey', 'wiki'));
+        throw new \moodle_exception(get_string('invalidsesskey', 'wiki'));
     }
     $comm = new page_wiki_handlecomments($wiki, $subwiki, $cm, 'modulepage');
     $comm->set_page($page);
@@ -80,7 +80,7 @@
         $comm = new page_wiki_handlecomments($wiki, $subwiki, $cm, 'modulepage');
         $comm->set_page($page);
         if (!confirm_sesskey()) {
-            print_error(get_string('invalidsesskey', 'wiki'));
+            throw new \moodle_exception(get_string('invalidsesskey', 'wiki'));
         }
     }
 }
diff --git a/mod/wiki/lock.php b/mod/wiki/lock.php
index 4955a7be7833b..5d8e169443255 100644
--- a/mod/wiki/lock.php
+++ b/mod/wiki/lock.php
@@ -38,38 +38,38 @@
 require_once($CFG->dirroot . '/mod/wiki/pagelib.php');
 
 if (!confirm_sesskey()) {
-    print_error('invalidsesskey');
+    throw new \moodle_exception('invalidsesskey');
 }
 
 $pageid = required_param('pageid', PARAM_INT);
 $section = optional_param('section', "", PARAM_TEXT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 
 if (!empty($section) && !$sectioncontent = wiki_get_section_page($page, $section)) {
-    print_error('invalidsection', 'wiki');
+    throw new \moodle_exception('invalidsection', 'wiki');
 }
 
 require_login($course, false, $cm);
 
 if (!wiki_user_can_edit($subwiki)) {
-    print_error('cannoteditpage', 'wiki');
+    throw new \moodle_exception('cannoteditpage', 'wiki');
 }
 
 $wikipage = new page_wiki_lock($wiki, $subwiki, $cm);
diff --git a/mod/wiki/map.php b/mod/wiki/map.php
index 9d32c031b0ec1..efd3aa9a9c026 100644
--- a/mod/wiki/map.php
+++ b/mod/wiki/map.php
@@ -40,23 +40,23 @@
 $option = optional_param('option', 0, PARAM_INT); // Option ID
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 require_course_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 $wikipage = new page_wiki_map($wiki, $subwiki, $cm, 'modulepage');
diff --git a/mod/wiki/overridelocks.php b/mod/wiki/overridelocks.php
index ea02d486e7f50..d40a48cf75593 100644
--- a/mod/wiki/overridelocks.php
+++ b/mod/wiki/overridelocks.php
@@ -41,25 +41,25 @@
 $section = optional_param('section', '', PARAM_TEXT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 
 if (!empty($section) && !$sectioncontent = wiki_get_section_page($page, $section)) {
-    print_error('invalidsection', 'wiki');
+    throw new \moodle_exception('invalidsection', 'wiki');
 }
 
 require_login($course, true, $cm);
@@ -67,7 +67,7 @@
 require_sesskey();
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 $context = context_module::instance($cm->id);
 require_capability('mod/wiki:overridelock', $context);
diff --git a/mod/wiki/pagelib.php b/mod/wiki/pagelib.php
index 16b9e22918581..cea90fef5c444 100644
--- a/mod/wiki/pagelib.php
+++ b/mod/wiki/pagelib.php
@@ -365,7 +365,7 @@ function set_url() {
             $params['swid'] = $this->subwiki->id;
             $params['title'] = $this->title;
         } else {
-            print_error(get_string('invalidparameters', 'wiki'));
+            throw new \moodle_exception(get_string('invalidparameters', 'wiki'));
         }
         $PAGE->set_url(new moodle_url($CFG->wwwroot . '/mod/wiki/view.php', $params));
     }
@@ -1205,7 +1205,7 @@ private function print_diff_content() {
 
             echo $this->wikioutput->diff($pageid, $oldversion, $newversion, array('total' => $total));
         } else {
-            print_error('versionerror', 'wiki');
+            throw new \moodle_exception('versionerror', 'wiki');
         }
     }
 }
@@ -2130,7 +2130,7 @@ protected function print_save() {
             $url = new moodle_url('/mod/wiki/view.php', array('pageid' => $this->page->id, 'group' => $this->subwiki->groupid));
             redirect($url);
         } else {
-            print_error('savingerror', 'wiki');
+            throw new \moodle_exception('savingerror', 'wiki');
         }
     }
 }
@@ -2220,7 +2220,7 @@ private function print_version_view() {
             echo $OUTPUT->box($content, 'generalbox wiki_contentbox');
 
         } else {
-            print_error('versionerror', 'wiki');
+            throw new \moodle_exception('versionerror', 'wiki');
         }
     }
 }
@@ -2247,7 +2247,7 @@ function print_content() {
                 wiki_restore_page($this->page, $version, $this->modcontext)) {
             redirect($CFG->wwwroot . '/mod/wiki/view.php?pageid=' . $this->page->id, get_string('restoring', 'wiki', $version->version), 3);
         } else {
-            print_error('restoreerror', 'wiki', $version->version);
+            throw new \moodle_exception('restoreerror', 'wiki', $version->version);
         }
     }
 
@@ -2345,7 +2345,7 @@ public function print_content() {
                 $this->delete_comment($this->commentid);
                 redirect($CFG->wwwroot . '/mod/wiki/comments.php?pageid=' . $this->page->id, get_string('deletecomment', 'wiki'), 2);
             } else {
-                print_error('nopermissiontoeditcomment');
+                throw new \moodle_exception('nopermissiontoeditcomment');
             }
         }
 
diff --git a/mod/wiki/prettyview.php b/mod/wiki/prettyview.php
index 7efc27b4be01d..728f25321fd0e 100644
--- a/mod/wiki/prettyview.php
+++ b/mod/wiki/prettyview.php
@@ -38,23 +38,23 @@
 $pageid = required_param('pageid', PARAM_INT); // Page ID
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 require_course_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 $wikipage = new page_wiki_prettyview($wiki, $subwiki, $cm);
diff --git a/mod/wiki/restoreversion.php b/mod/wiki/restoreversion.php
index 2f5302a32d299..05d538ae1dab3 100644
--- a/mod/wiki/restoreversion.php
+++ b/mod/wiki/restoreversion.php
@@ -41,19 +41,19 @@
 $confirm = optional_param('confirm', 0, PARAM_BOOL);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
@@ -61,12 +61,12 @@
 require_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 if ($confirm) {
     if (!confirm_sesskey()) {
-        print_error(get_string('invalidsesskey', 'wiki'));
+        throw new \moodle_exception(get_string('invalidsesskey', 'wiki'));
     }
     $wikipage = new page_wiki_confirmrestore($wiki, $subwiki, $cm);
     $wikipage->set_page($page);
diff --git a/mod/wiki/search.php b/mod/wiki/search.php
index 17b8d2dfd57eb..564b5fe1ca406 100644
--- a/mod/wiki/search.php
+++ b/mod/wiki/search.php
@@ -34,24 +34,24 @@
 $userid = optional_param('uid', 0, PARAM_INT);
 
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 if (!$cm = get_coursemodule_from_id('wiki', $cmid)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 require_login($course, true, $cm);
 
 // Checking wiki instance
 if (!$wiki = wiki_get_wiki($cm->instance)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if ($subwikiid) {
     // Subwiki id is specified.
     $subwiki = wiki_get_subwiki($subwikiid);
     if (!$subwiki || $subwiki->wikiid != $wiki->id) {
-        print_error('incorrectsubwikiid', 'wiki');
+        throw new \moodle_exception('incorrectsubwikiid', 'wiki');
     }
 } else {
     // Getting current group id
@@ -72,7 +72,7 @@
 }
 
 if ($subwiki && !wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 $wikipage = new page_wiki_search($wiki, $subwiki, $cm);
diff --git a/mod/wiki/view.php b/mod/wiki/view.php
index 5bd2744d23095..c808af72f0b2e 100644
--- a/mod/wiki/view.php
+++ b/mod/wiki/view.php
@@ -65,7 +65,7 @@
 if ($id) {
     // Cheacking course module instance
     if (!$cm = get_coursemodule_from_id('wiki', $id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     // Checking course instance
@@ -75,7 +75,7 @@
 
     // Checking wiki instance
     if (!$wiki = wiki_get_wiki($cm->instance)) {
-        print_error('incorrectwikiid', 'wiki');
+        throw new \moodle_exception('incorrectwikiid', 'wiki');
     }
     $PAGE->set_cm($cm);
 
@@ -120,22 +120,22 @@
 
     // Checking page instance
     if (!$page = wiki_get_page($pageid)) {
-        print_error('incorrectpageid', 'wiki');
+        throw new \moodle_exception('incorrectpageid', 'wiki');
     }
 
     // Checking subwiki
     if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-        print_error('incorrectsubwikiid', 'wiki');
+        throw new \moodle_exception('incorrectsubwikiid', 'wiki');
     }
 
     // Checking wiki instance of that subwiki
     if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-        print_error('incorrectwikiid', 'wiki');
+        throw new \moodle_exception('incorrectwikiid', 'wiki');
     }
 
     // Checking course module instance
     if (!$cm = get_coursemodule_from_instance("wiki", $subwiki->wikiid)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     $currentgroup = $subwiki->groupid;
@@ -163,12 +163,12 @@
 
     // Setting wiki instance
     if (!$wiki = wiki_get_wiki($wid)) {
-        print_error('incorrectwikiid', 'wiki');
+        throw new \moodle_exception('incorrectwikiid', 'wiki');
     }
 
     // Checking course module
     if (!$cm = get_coursemodule_from_instance("wiki", $wiki->id)) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
 
     // Checking course instance
@@ -207,7 +207,7 @@
         $manageandedit = $manage && $edit;
 
         if ($groupmode == VISIBLEGROUPS and ($modeanduser || $modeandgroupmember) and !$manageandedit) {
-            print_error('nocontent','wiki');
+            throw new \moodle_exception('nocontent', 'wiki');
         }
 
         $params = array('wid' => $wiki->id, 'group' => $gid, 'uid' => $uid, 'title' => $title);
@@ -241,7 +241,7 @@
     //
     //    // Checking wiki instance
     //    if (!$wiki = wiki_get_wiki($wid)) {
-    //        print_error('incorrectwikiid', 'wiki');
+    //        throw new \moodle_exception('incorrectwikiid', 'wiki');
     //    }
     //
     //    // Checking subwiki instance
@@ -250,7 +250,7 @@
     //        $currentgroup = 0;
     //    }
     //    if (!$subwiki = wiki_get_subwiki_by_group($wid, $currentgroup)) {
-    //        print_error('incorrectsubwikiid', 'wiki');
+    //        throw new \moodle_exception('incorrectsubwikiid', 'wiki');
     //    }
     //
     //    // Checking page instance
@@ -263,7 +263,7 @@
     //
     //    // Checking course module instance
     //    if (!$cm = get_coursemodule_from_instance("wiki", $wiki->id, $course->id)) {
-    //        print_error('invalidcoursemodule');
+    //        throw new \moodle_exception('invalidcoursemodule');
     //    }
     //
     //    $subwiki = null;
@@ -275,11 +275,11 @@
     //     * Error. No more options
     //     */
 } else {
-    print_error('invalidparameters', 'wiki');
+    throw new \moodle_exception('invalidparameters', 'wiki');
 }
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 if (($edit != - 1) and $PAGE->user_allowed_editing()) {
diff --git a/mod/wiki/viewversion.php b/mod/wiki/viewversion.php
index 5fad2fdac4963..94147ac7fade9 100644
--- a/mod/wiki/viewversion.php
+++ b/mod/wiki/viewversion.php
@@ -41,19 +41,19 @@
 $versionid = required_param('versionid', PARAM_INT);
 
 if (!$page = wiki_get_page($pageid)) {
-    print_error('incorrectpageid', 'wiki');
+    throw new \moodle_exception('incorrectpageid', 'wiki');
 }
 
 if (!$subwiki = wiki_get_subwiki($page->subwikiid)) {
-    print_error('incorrectsubwikiid', 'wiki');
+    throw new \moodle_exception('incorrectsubwikiid', 'wiki');
 }
 
 if (!$wiki = wiki_get_wiki($subwiki->wikiid)) {
-    print_error('incorrectwikiid', 'wiki');
+    throw new \moodle_exception('incorrectwikiid', 'wiki');
 }
 
 if (!$cm = get_coursemodule_from_instance('wiki', $wiki->id)) {
-    print_error('invalidcoursemodule');
+    throw new \moodle_exception('invalidcoursemodule');
 }
 
 $course = $DB->get_record('course', array('id' => $cm->course), '*', MUST_EXIST);
@@ -61,7 +61,7 @@
 require_course_login($course, true, $cm);
 
 if (!wiki_user_can_view($subwiki, $wiki)) {
-    print_error('cannotviewpage', 'wiki');
+    throw new \moodle_exception('cannotviewpage', 'wiki');
 }
 
 $wikipage = new page_wiki_viewversion($wiki, $subwiki, $cm, 'modulepage');
diff --git a/mod/workshop/assessment.php b/mod/workshop/assessment.php
index 7ba7845660022..7e71af903eda9 100644
--- a/mod/workshop/assessment.php
+++ b/mod/workshop/assessment.php
@@ -46,7 +46,7 @@
 
 require_login($course, false, $cm);
 if (isguestuser()) {
-    print_error('guestsarenotallowed');
+    throw new \moodle_exception('guestsarenotallowed');
 }
 $workshop = new workshop($workshop, $cm, $course);
 
diff --git a/mod/workshop/editformpreview.php b/mod/workshop/editformpreview.php
index bb5c42e671b97..8a950a355748c 100644
--- a/mod/workshop/editformpreview.php
+++ b/mod/workshop/editformpreview.php
@@ -33,7 +33,7 @@
 
 require_login($course, false, $cm);
 if (isguestuser()) {
-    print_error('guestsarenotallowed');
+    throw new \moodle_exception('guestsarenotallowed');
 }
 $workshop = new workshop($workshop, $cm, $course);
 
diff --git a/mod/workshop/exassessment.php b/mod/workshop/exassessment.php
index a890ca6901fb4..d8938552837a8 100644
--- a/mod/workshop/exassessment.php
+++ b/mod/workshop/exassessment.php
@@ -35,7 +35,7 @@
 
 require_login($course, false, $cm);
 if (isguestuser()) {
-    print_error('guestsarenotallowed');
+    throw new \moodle_exception('guestsarenotallowed');
 }
 $workshop = new workshop($workshop, $cm, $course);
 
@@ -52,7 +52,7 @@
 if ($isreviewer or $canmanage) {
     // such a user can continue
 } else {
-    print_error('nopermissions', 'error', $workshop->view_url(), 'assess example submission');
+    throw new \moodle_exception('nopermissions', 'error', $workshop->view_url(), 'assess example submission');
 }
 
 // only the reviewer is allowed to modify the assessment
diff --git a/mod/workshop/excompare.php b/mod/workshop/excompare.php
index 73545af1e596d..5157ca2d717cd 100644
--- a/mod/workshop/excompare.php
+++ b/mod/workshop/excompare.php
@@ -34,7 +34,7 @@
 
 require_login($course, false, $cm);
 if (isguestuser()) {
-    print_error('guestsarenotallowed');
+    throw new \moodle_exception('guestsarenotallowed');
 }
 
 $workshop = $DB->get_record('workshop', array('id' => $cm->instance), '*', MUST_EXIST);
@@ -46,7 +46,7 @@
 $example    = $workshop->get_example_by_id($sid);
 $assessment = $workshop->get_assessment_by_id($aid);
 if ($assessment->submissionid != $example->id) {
-   print_error('invalidarguments');
+    throw new \moodle_exception('invalidarguments');
 }
 $mformassessment = $strategy->get_assessment_form($PAGE->url, 'assessment', $assessment, false);
 if ($refasid = $DB->get_field('workshop_assessments', 'id', array('submissionid' => $example->id, 'weight' => 1))) {
@@ -62,7 +62,7 @@
 } elseif ($isreviewer and $workshop->assessing_examples_allowed()) {
     // ok you can go
 } else {
-    print_error('nopermissions', 'error', $workshop->view_url(), 'compare example assessment');
+    throw new \moodle_exception('nopermissions', 'error', $workshop->view_url(), 'compare example assessment');
 }
 
 $PAGE->set_title($workshop->name);
diff --git a/mod/workshop/exsubmission.php b/mod/workshop/exsubmission.php
index 4aeb1162a078b..fb98f2c0ae07a 100644
--- a/mod/workshop/exsubmission.php
+++ b/mod/workshop/exsubmission.php
@@ -38,7 +38,7 @@
 
 require_login($course, false, $cm);
 if (isguestuser()) {
-    print_error('guestsarenotallowed');
+    throw new \moodle_exception('guestsarenotallowed');
 }
 
 $workshop = $DB->get_record('workshop', array('id' => $cm->instance), '*', MUST_EXIST);
@@ -74,7 +74,7 @@
 } elseif (is_null($example->id) and $canmanage) {
     // ok you can go
 } else {
-    print_error('nopermissions', 'error', $workshop->view_url(), 'view or manage example submission');
+    throw new \moodle_exception('nopermissions', 'error', $workshop->view_url(), 'view or manage example submission');
 }
 
 if ($id and $delete and $confirm and $canmanage) {
diff --git a/mod/workshop/locallib.php b/mod/workshop/locallib.php
index 15d7a65ade9f8..8d36065667c44 100644
--- a/mod/workshop/locallib.php
+++ b/mod/workshop/locallib.php
@@ -3039,12 +3039,13 @@ public function check_view_assessment($assessment, $submission) {
         $canviewallsubmissions = $canviewallsubmissions && $this->check_group_membership($submission->authorid);
 
         if (!$isreviewer and !$isauthor and !($canviewallassessments and $canviewallsubmissions)) {
-            print_error('nopermissions', 'error', $this->view_url(), 'view this assessment');
+            throw new \moodle_exception('nopermissions', 'error', $this->view_url(), 'view this assessment');
         }
 
         if ($isauthor and !$isreviewer and !$canviewallassessments and $this->phase != self::PHASE_CLOSED) {
             // Authors can see assessments of their work at the end of workshop only.
-            print_error('nopermissions', 'error', $this->view_url(), 'view assessment of own work before workshop is closed');
+            throw new \moodle_exception('nopermissions', 'error', $this->view_url(),
+                'view assessment of own work before workshop is closed');
         }
     }
 
diff --git a/mod/workshop/submission.php b/mod/workshop/submission.php
index 0b92ee326f5f1..71c9b446a5913 100644
--- a/mod/workshop/submission.php
+++ b/mod/workshop/submission.php
@@ -37,7 +37,7 @@
 
 require_login($course, false, $cm);
 if (isguestuser()) {
-    print_error('guestsarenotallowed');
+    throw new \moodle_exception('guestsarenotallowed');
 }
 
 $workshoprecord = $DB->get_record('workshop', array('id' => $cm->instance), '*', MUST_EXIST);
@@ -121,7 +121,7 @@
 } elseif (is_null($submission->id) and $cansubmit) {
     // ok you can go
 } else {
-    print_error('nopermissions', 'error', $workshop->view_url(), 'view or create submission');
+    throw new \moodle_exception('nopermissions', 'error', $workshop->view_url(), 'view or create submission');
 }
 
 if ($submission->id) {
diff --git a/mod/workshop/switchphase.php b/mod/workshop/switchphase.php
index 60bcef9f78127..2d0432c74118b 100644
--- a/mod/workshop/switchphase.php
+++ b/mod/workshop/switchphase.php
@@ -45,7 +45,7 @@
         throw new moodle_exception('confirmsesskeybad');
     }
     if (!$workshop->switch_phase($phase)) {
-        print_error('errorswitchingphase', 'workshop', $workshop->view_url());
+        throw new \moodle_exception('errorswitchingphase', 'workshop', $workshop->view_url());
     }
     redirect($workshop->view_url());
 }
diff --git a/my/index.php b/my/index.php
index 7979644cf98d4..a620fad8dfe0a 100644
--- a/my/index.php
+++ b/my/index.php
@@ -86,7 +86,7 @@
 
 // Get the My Moodle page info.  Should always return something unless the database is broken.
 if (!$currentpage = my_get_page($userid, MY_PAGE_PRIVATE)) {
-    print_error('mymoodlesetup');
+    throw new \moodle_exception('mymoodlesetup');
 }
 
 // Start setting up the page
@@ -120,7 +120,7 @@
         if (!is_null($userid)) {
             require_sesskey();
             if (!$currentpage = my_reset_page($userid, MY_PAGE_PRIVATE)) {
-                print_error('reseterror', 'my');
+                throw new \moodle_exception('reseterror', 'my');
             }
             redirect(new moodle_url('/my'));
         }
@@ -137,7 +137,7 @@
             // For the page to display properly with the user context header the page blocks need to
             // be copied over to the user context.
             if (!$currentpage = my_copy_page($USER->id, MY_PAGE_PRIVATE)) {
-                print_error('mymoodlesetup');
+                throw new \moodle_exception('mymoodlesetup');
             }
             $context = context_user::instance($USER->id);
             $PAGE->set_context($context);
diff --git a/my/indexsys.php b/my/indexsys.php
index 0688ddf1383ef..1cabd4ab54a1f 100644
--- a/my/indexsys.php
+++ b/my/indexsys.php
@@ -74,7 +74,7 @@
 
 // Get the My Moodle page info.  Should always return something unless the database is broken.
 if (!$currentpage = my_get_page(null, MY_PAGE_PRIVATE)) {
-    print_error('mymoodlesetup');
+    throw new \moodle_exception('mymoodlesetup');
 }
 $PAGE->set_subpage($currentpage->id);
 
diff --git a/notes/delete.php b/notes/delete.php
index cb184b5497778..eebec2a3583f7 100644
--- a/notes/delete.php
+++ b/notes/delete.php
@@ -23,27 +23,27 @@
 $PAGE->set_url('/notes/delete.php', array('id' => $noteid));
 
 if (!$note = note_load($noteid)) {
-    print_error('invalidid');
+    throw new \moodle_exception('invalidid');
 }
 
 if (!$course = $DB->get_record('course', array('id' => $note->courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
 
 if (empty($CFG->enablenotes)) {
-    print_error('notesdisabled', 'notes');
+    throw new \moodle_exception('notesdisabled', 'notes');
 }
 
 if (!$user = $DB->get_record('user', array('id' => $note->userid))) {
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 $context = context_course::instance($course->id);
 
 if (!has_capability('moodle/notes:manage', $context)) {
-    print_error('nopermissiontodelete', 'notes');
+    throw new \moodle_exception('nopermissiontodelete', 'notes');
 }
 
 if (data_submitted() && confirm_sesskey()) {
diff --git a/notes/edit.php b/notes/edit.php
index 7b97ecc250f63..5d7970f404731 100644
--- a/notes/edit.php
+++ b/notes/edit.php
@@ -27,7 +27,7 @@
     // Existing note.
     $url->param('id', $noteid);
     if (!$note = note_load($noteid)) {
-        print_error('invalidid', 'notes');
+        throw new \moodle_exception('invalidid', 'notes');
     }
 
 } else {
@@ -51,20 +51,20 @@
 $PAGE->set_url($url);
 
 if (!$course = $DB->get_record('course', array('id' => $note->courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course);
 
 if (empty($CFG->enablenotes)) {
-    print_error('notesdisabled', 'notes');
+    throw new \moodle_exception('notesdisabled', 'notes');
 }
 
 $context = context_course::instance($course->id);
 require_capability('moodle/notes:manage', $context);
 
 if (!$user = $DB->get_record('user', array('id' => $note->userid))) {
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 $noteform = new note_edit_form();
diff --git a/notes/index.php b/notes/index.php
index 1ae4c2b00262f..585028f447313 100644
--- a/notes/index.php
+++ b/notes/index.php
@@ -30,7 +30,7 @@
 $filterselect = optional_param('filterselect', 0, PARAM_INT);
 
 if (empty($CFG->enablenotes)) {
-    print_error('notesdisabled', 'notes');
+    throw new \moodle_exception('notesdisabled', 'notes');
 }
 
 $url = new moodle_url('/notes/index.php');
diff --git a/portfolio/add.php b/portfolio/add.php
index b18ff4224cef5..d3c233a216228 100644
--- a/portfolio/add.php
+++ b/portfolio/add.php
@@ -25,7 +25,7 @@
 require_once(__DIR__ . '/../config.php');
 
 if (empty($CFG->enableportfolios)) {
-    print_error('disabled', 'portfolio');
+    throw new \moodle_exception('disabled', 'portfolio');
 }
 
 require_once($CFG->libdir . '/portfoliolib.php');
diff --git a/portfolio/download/file.php b/portfolio/download/file.php
index 0372b0eb4f2ec..c183191580b85 100644
--- a/portfolio/download/file.php
+++ b/portfolio/download/file.php
@@ -7,7 +7,7 @@
 require(__DIR__.'/../../config.php');
 
 if (empty($CFG->enableportfolios)) {
-    print_error('disabled', 'portfolio');
+    throw new \moodle_exception('disabled', 'portfolio');
 }
 
 require_once($CFG->libdir.'/portfoliolib.php');
diff --git a/portfolio/file.php b/portfolio/file.php
index bcb1e7dc6b9b1..f4b1c149f1c74 100644
--- a/portfolio/file.php
+++ b/portfolio/file.php
@@ -27,7 +27,7 @@
 require_once(__DIR__ . '/../config.php');
 
 if (empty($CFG->enableportfolios)) {
-    print_error('disabled', 'portfolio');
+    throw new \moodle_exception('disabled', 'portfolio');
 }
 
 require_once($CFG->libdir . '/portfoliolib.php');
diff --git a/portfolio/mahara/preconfig.php b/portfolio/mahara/preconfig.php
index 127a1a7c1bdcf..5bde0ee6b3dbf 100644
--- a/portfolio/mahara/preconfig.php
+++ b/portfolio/mahara/preconfig.php
@@ -27,7 +27,7 @@
 require_once(__DIR__ . '/../../config.php');
 
 if (empty($CFG->enableportfolios)) {
-    print_error('disabled', 'portfolio');
+    throw new \moodle_exception('disabled', 'portfolio');
 }
 
 require_once($CFG->libdir . '/portfoliolib.php');
diff --git a/question/classes/external.php b/question/classes/external.php
index 6df4d88e5164f..9d535c23c23c7 100644
--- a/question/classes/external.php
+++ b/question/classes/external.php
@@ -166,7 +166,7 @@ public static function submit_tags_form($questionid, $contextid, $formdata) {
                 FROM {question} q
                 JOIN {question_categories} qc ON qc.id = q.category
                 WHERE q.id = ?', [$questionid])) {
-            print_error('questiondoesnotexist', 'question');
+            throw new \moodle_exception('questiondoesnotexist', 'question');
         }
 
         require_once($CFG->libdir . '/questionlib.php');
diff --git a/question/editlib.php b/question/editlib.php
index 4f739c7499e2a..1bc9a64bff893 100644
--- a/question/editlib.php
+++ b/question/editlib.php
@@ -40,9 +40,9 @@ function get_module_from_cmid($cmid) {
                                     {modules} md
                                WHERE cm.id = ? AND
                                      md.id = cm.module", array($cmid))){
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     } elseif (!$modrec =$DB->get_record($cmrec->modname, array('id' => $cmrec->instance))) {
-        print_error('invalidcoursemodule');
+        throw new \moodle_exception('invalidcoursemodule');
     }
     $modrec->instance = $modrec->id;
     $modrec->cmid = $cmrec->id;
@@ -392,7 +392,7 @@ function question_build_edit_resources($edittab, $baseurl, $params,
         $catparts = explode(',', $pagevars['cat']);
         if (!$catparts[0] || (false !== array_search($catparts[1], $contextlistarr)) ||
                 !$DB->count_records_select("question_categories", "id = ? AND contextid = ?", array($catparts[0], $catparts[1]))) {
-            print_error('invalidcategory', 'question');
+            throw new \moodle_exception('invalidcategory', 'question');
         }
     } else {
         $category = $defaultcategory;
@@ -492,12 +492,12 @@ function require_login_in_context($contextorid = null){
     } else if ($context && ($context->contextlevel == CONTEXT_MODULE)) {
         if ($cm = $DB->get_record('course_modules',array('id' =>$context->instanceid))) {
             if (!$course = $DB->get_record('course', array('id' => $cm->course))) {
-                print_error('invalidcourseid');
+                throw new \moodle_exception('invalidcourseid');
             }
             require_course_login($course, true, $cm);
 
         } else {
-            print_error('invalidcoursemodule');
+            throw new \moodle_exception('invalidcoursemodule');
         }
     } else if ($context && ($context->contextlevel == CONTEXT_SYSTEM)) {
         if (!empty($CFG->forcelogin)) {
diff --git a/question/format.php b/question/format.php
index 89105cb256b9b..620fc55f41182 100644
--- a/question/format.php
+++ b/question/format.php
@@ -1029,7 +1029,7 @@ public function exportprocess($checkcapabilities = true) {
 
         // did we actually process anything
         if ($count==0) {
-            print_error('noquestions', 'question', $continuepath);
+            throw new \moodle_exception('noquestions', 'question', $continuepath);
         }
 
         // final pre-process on exported data
@@ -1066,7 +1066,7 @@ protected function get_category_path($id, $includecontext = true) {
         global $DB;
 
         if (!$category = $DB->get_record('question_categories', array('id' => $id))) {
-            print_error('cannotfindcategory', 'error', '', $id);
+            throw new \moodle_exception('cannotfindcategory', 'error', '', $id);
         }
         $contextstring = $this->translator->context_to_string($category->contextid);
 
diff --git a/question/type/calculated/questiontype.php b/question/type/calculated/questiontype.php
index ba00ffa773903..84b1ce23933c1 100644
--- a/question/type/calculated/questiontype.php
+++ b/question/type/calculated/questiontype.php
@@ -380,7 +380,7 @@ public function print_next_wizard_page($question, $form, $course) {
                 require("{$CFG->dirroot}/question/type/calculated/datasetitems.php");
                 break;
             default:
-                print_error('invalidwizardpage', 'question');
+                throw new \moodle_exception('invalidwizardpage', 'question');
                 break;
         }
     }
@@ -412,7 +412,7 @@ public function &next_wizard_form($submiturl, $question, $wizardnow) {
                         "{$submiturl}?wizardnow=datasetitems", $question, $regenerate);
                 break;
             default:
-                print_error('invalidwizardpage', 'question');
+                throw new \moodle_exception('invalidwizardpage', 'question');
                 break;
         }
 
@@ -685,7 +685,7 @@ public function save_question($question, $form) {
                 $this->save_question_calculated($question, $form);
                 break;
             default:
-                print_error('invalidwizardpage', 'question');
+                throw new \moodle_exception('invalidwizardpage', 'question');
                 break;
         }
         return $question;
@@ -1042,7 +1042,7 @@ public function generate_dataset_item($options) {
             return sprintf("%.".$regs[4].'f', $nbr);
 
         } else {
-            print_error('disterror', 'question', '', $regs[1]);
+            throw new \moodle_exception('disterror', 'question', '', $regs[1]);
         }
         return '';
     }
@@ -1476,7 +1476,7 @@ public function pick_question_dataset($question, $datasetitem) {
             $a = new stdClass();
             $a->id = $question->id;
             $a->item = $datasetitem;
-            print_error('cannotgetdsfordependent', 'question', '', $a);
+            throw new \moodle_exception('cannotgetdsfordependent', 'question', '', $a);
         }
         $dataset = Array();
         foreach ($dataitems as $id => $dataitem) {
diff --git a/question/type/multianswer/edit_multianswer_form.php b/question/type/multianswer/edit_multianswer_form.php
index 02a625cea4d29..2f1c618cb4427 100644
--- a/question/type/multianswer/edit_multianswer_form.php
+++ b/question/type/multianswer/edit_multianswer_form.php
@@ -280,7 +280,7 @@ public function set_data($question) {
                             case 'subquestion_replacement':
                                 continue 2;
                             default:
-                                print_error('unknownquestiontype', 'question', '',
+                                throw new \moodle_exception('unknownquestiontype', 'question', '',
                                         $wrapped->qtype);
                         }
                         $separator = '';
diff --git a/question/type/multianswer/questiontype.php b/question/type/multianswer/questiontype.php
index 8e511ed474b22..d750bfd4e4235 100644
--- a/question/type/multianswer/questiontype.php
+++ b/question/type/multianswer/questiontype.php
@@ -501,7 +501,7 @@ function qtype_multianswer_extract_question($text) {
             $wrapped->shuffleanswers = 1;
             $wrapped->layout = qtype_multichoice_base::LAYOUT_HORIZONTAL;
         } else {
-            print_error('unknownquestiontype', 'question', '', $answerregs[2]);
+            throw new \moodle_exception('unknownquestiontype', 'question', '', $answerregs[2]);
             return false;
         }
 
diff --git a/question/type/questiontypebase.php b/question/type/questiontypebase.php
index c6c6bff8e11b2..c0328ec0227e2 100644
--- a/question/type/questiontypebase.php
+++ b/question/type/questiontypebase.php
@@ -538,7 +538,7 @@ public function save_question($question, $form) {
         $result = $this->save_question_options($form);
 
         if (!empty($result->error)) {
-            print_error($result->error);
+            throw new \moodle_exception($result->error);
         }
 
         if (!empty($result->notice)) {
diff --git a/rating/index.php b/rating/index.php
index 0851dde45db3e..493180000b1f6 100644
--- a/rating/index.php
+++ b/rating/index.php
@@ -62,7 +62,7 @@
                 'scaleid' => $scaleid);
 if (!has_capability('moodle/rating:view', $context) ||
         !component_callback($component, 'rating_can_see_item_ratings', array($params), true)) {
-    print_error('noviewrate', 'rating');
+    throw new \moodle_exception('noviewrate', 'rating');
 }
 
 $canviewallratings = has_capability('moodle/rating:viewall', $context);
diff --git a/rating/rate.php b/rating/rate.php
index 0ec08c8c624c3..a8bd265aa9b07 100644
--- a/rating/rate.php
+++ b/rating/rate.php
@@ -47,7 +47,7 @@
 $PAGE->set_url('/rating/rate.php', array('contextid' => $context->id));
 
 if (!confirm_sesskey() || !has_capability('moodle/rating:rate', $context)) {
-    print_error('ratepermissiondenied', 'rating');
+    throw new \moodle_exception('ratepermissiondenied', 'rating');
 }
 
 $rm = new rating_manager();
@@ -57,7 +57,7 @@
 $pluginpermissionsarray = $rm->get_plugin_permissions_array($context->id, $component, $ratingarea);
 
 if (!$pluginpermissionsarray['rate']) {
-    print_error('ratepermissiondenied', 'rating');
+    throw new \moodle_exception('ratepermissiondenied', 'rating');
 } else {
     $params = array(
         'context'     => $context,
diff --git a/report/completion/index.php b/report/completion/index.php
index 85b73fa947437..d114d809e7c41 100644
--- a/report/completion/index.php
+++ b/report/completion/index.php
@@ -93,7 +93,7 @@
 $completion = new completion_info($course);
 
 if (!$completion->has_criteria()) {
-    print_error('nocriteriaset', 'completion', $CFG->wwwroot.'/course/report.php?id='.$course->id);
+    throw new \moodle_exception('nocriteriaset', 'completion', $CFG->wwwroot.'/course/report.php?id='.$course->id);
 }
 
 // Get criteria and put in correct order
diff --git a/report/completion/user.php b/report/completion/user.php
index 47af8428958a6..520a11077e7ca 100644
--- a/report/completion/user.php
+++ b/report/completion/user.php
@@ -47,7 +47,7 @@
 
 if (!report_completion_can_access_user_report($user, $course)) {
     // this should never happen
-    print_error('nocapability', 'report_completion');
+    throw new \moodle_exception('nocapability', 'report_completion');
 }
 
 $stractivityreport = get_string('activityreport');
diff --git a/report/courseoverview/index.php b/report/courseoverview/index.php
index 316a2d8704816..ba1b0a8f9f83a 100644
--- a/report/courseoverview/index.php
+++ b/report/courseoverview/index.php
@@ -37,7 +37,7 @@
     if (has_capability('moodle/site:config', $systemcontext)) {
         redirect("$CFG->wwwroot/$CFG->admin/search.php?query=enablestats", get_string('mustenablestats', 'admin'), 3);
     } else {
-        print_error('statsdisable');
+        throw new \moodle_exception('statsdisable');
     }
 }
 
@@ -67,7 +67,7 @@
 $timeoptions = stats_get_time_options($now,$lastweekend,$lastmonthend,$earliestday,$earliestweek,$earliestmonth);
 
 if (empty($timeoptions)) {
-    print_error('nostatstodisplay', 'error', $CFG->wwwroot.'/course/view.php?id='.$course->id);
+    throw new \moodle_exception('nostatstodisplay', 'error', $CFG->wwwroot.'/course/view.php?id='.$course->id);
 }
 
 echo html_writer::start_tag('form', array('action' => 'index.php', 'method' => 'post', 'class' => 'form-inline'));
diff --git a/report/courseoverview/locallib.php b/report/courseoverview/locallib.php
index 5e97febab250e..b957d7813f23a 100644
--- a/report/courseoverview/locallib.php
+++ b/report/courseoverview/locallib.php
@@ -54,7 +54,7 @@ function report_courseoverview_print_chart($report, $time, $numcourses) {
 
     if (empty($courses)) {
         $PAGE->set_url('/report/courseoverview/index.php');
-        print_error('statsnodata', 'error', $PAGE->url->out());
+        throw new \moodle_exception('statsnodata', 'error', $PAGE->url->out());
     }
 
     $data = [];
diff --git a/report/eventlist/eventdetail.php b/report/eventlist/eventdetail.php
index ac72b1c66cb3c..9f1566740e38e 100644
--- a/report/eventlist/eventdetail.php
+++ b/report/eventlist/eventdetail.php
@@ -34,7 +34,7 @@
 
 // Check that $eventname is a valid event.
 if (!array_key_exists($eventname, $completelist)) {
-    print_error('errorinvalidevent', 'report_eventlist');
+    throw new \moodle_exception('errorinvalidevent', 'report_eventlist');
 }
 
 // Break up the full event name to usable parts.
@@ -45,7 +45,7 @@
 $directory = $directory . '/classes/event';
 // Verify that the directory is valid.
 if (!is_dir($directory)) {
-    print_error('errorinvaliddirectory', 'report_eventlist');
+    throw new \moodle_exception('errorinvaliddirectory', 'report_eventlist');
 }
 $filename = end($component);
 $eventfiles = $directory . '/' . $filename . '.php';
diff --git a/report/log/user.php b/report/log/user.php
index 82d86329d1960..4bd72c6143541 100644
--- a/report/log/user.php
+++ b/report/log/user.php
@@ -59,7 +59,7 @@
 list($all, $today) = report_log_can_access_user_report($user, $course);
 
 if (!$today && !$all) {
-    print_error('nocapability', 'report_log');
+    throw new \moodle_exception('nocapability', 'report_log');
 }
 
 if ($mode === 'today') {
diff --git a/report/outline/user.php b/report/outline/user.php
index 2731b0421a133..9b6e717d6c50a 100644
--- a/report/outline/user.php
+++ b/report/outline/user.php
@@ -56,7 +56,7 @@
 $PAGE->set_url('/report/outline/user.php', array('id'=>$userid, 'course'=>$courseid, 'mode'=>$mode));
 
 if (!report_outline_can_access_user_report($user, $course)) {
-    print_error('nocapability', 'report_outline');
+    throw new \moodle_exception('nocapability', 'report_outline');
 }
 
 $stractivityreport = get_string('activityreport');
diff --git a/report/participation/index.php b/report/participation/index.php
index e718bc2023377..f2b2f70878ece 100644
--- a/report/participation/index.php
+++ b/report/participation/index.php
@@ -58,11 +58,11 @@
 }
 
 if (!$course = $DB->get_record('course', array('id'=>$id))) {
-    print_error('invalidcourse');
+    throw new \moodle_exception('invalidcourse');
 }
 
 if ($roleid != 0 and !$role = $DB->get_record('role', array('id'=>$roleid))) {
-    print_error('invalidrole');
+    throw new \moodle_exception('invalidrole');
 }
 
 require_login($course);
diff --git a/report/progress/index.php b/report/progress/index.php
index db2920a1d6ac0..9562f512db24d 100644
--- a/report/progress/index.php
+++ b/report/progress/index.php
@@ -33,7 +33,7 @@
 $id = required_param('course',PARAM_INT);
 $course = $DB->get_record('course',array('id'=>$id));
 if (!$course) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 $context = context_course::instance($course->id);
 
diff --git a/report/stats/index.php b/report/stats/index.php
index 21591702e742b..6b4241b9bd02a 100644
--- a/report/stats/index.php
+++ b/report/stats/index.php
@@ -50,7 +50,7 @@
 }
 
 if (!$course = $DB->get_record("course", array("id"=>$courseid))) {
-    print_error("invalidcourseid");
+    throw new \moodle_exception("invalidcourseid");
 }
 
 if (!empty($userid)) {
@@ -100,7 +100,7 @@
     if (has_capability('moodle/site:config', context_system::instance())) {
         redirect("$CFG->wwwroot/$CFG->admin/settings.php?section=stats", get_string('mustenablestats', 'admin'), 3);
     } else {
-        print_error('statsdisable');
+        throw new \moodle_exception('statsdisable');
     }
 }
 
diff --git a/report/stats/locallib.php b/report/stats/locallib.php
index 18c47b09d2e17..f629de7cab0a1 100644
--- a/report/stats/locallib.php
+++ b/report/stats/locallib.php
@@ -34,7 +34,7 @@ function report_stats_mode_menu($course, $mode, $time, $url) {
     $reportoptions = stats_get_report_options($course->id, $mode);
     $timeoptions = report_stats_timeoptions($mode);
     if (empty($timeoptions)) {
-        print_error('nostatstodisplay', '', $CFG->wwwroot.'/course/view.php?id='.$course->id);
+        throw new \moodle_exception('nostatstodisplay', '', $CFG->wwwroot.'/course/view.php?id='.$course->id);
     }
     */
 
@@ -119,7 +119,7 @@ function report_stats_report($course, $report, $mode, $user, $roleid, $time) {
     $reportoptions = stats_get_report_options($course->id, $mode);
     $timeoptions = report_stats_timeoptions($mode);
     if (empty($timeoptions)) {
-        print_error('nostatstodisplay', '', $CFG->wwwroot.'/course/view.php?id='.$course->id);
+        throw new \moodle_exception('nostatstodisplay', '', $CFG->wwwroot.'/course/view.php?id='.$course->id);
     }
 
     $users = array();
@@ -148,7 +148,7 @@ function report_stats_report($course, $report, $mode, $user, $roleid, $time) {
         $sql .= " ORDER BY {$sort}";
 
         if (!$us = $DB->get_records_sql($sql, array_merge($param->params, $moreparams))) {
-            print_error('nousers');
+            throw new \moodle_exception('nousers');
         }
         foreach ($us as $u) {
             $users[$u->id] = fullname($u, true);
@@ -188,7 +188,7 @@ function report_stats_report($course, $report, $mode, $user, $roleid, $time) {
     //  - If the mode is not detailed OR a valid user has been selected.
     if (!empty($report) && !empty($time) && ($mode !== STATS_MODE_DETAILED || !empty($userid))) {
         if ($report == STATS_REPORT_LOGINS && $course->id != SITEID) {
-            print_error('reportnotavailable');
+            throw new \moodle_exception('reportnotavailable');
         }
 
         $param = stats_get_parameters($time, $report, $course->id, $mode, $roleid);
diff --git a/report/stats/user.php b/report/stats/user.php
index 4ee56e5ab5c14..84cc0641387a2 100644
--- a/report/stats/user.php
+++ b/report/stats/user.php
@@ -53,7 +53,7 @@
 
 if (!report_stats_can_access_user_report($user, $course)) {
     // this should never happen
-    print_error('nocapability', 'report_stats');
+    throw new \moodle_exception('nocapability', 'report_stats');
 }
 
 $stractivityreport = get_string('activityreport');
@@ -90,7 +90,7 @@
 $event->trigger();
 
 if (empty($CFG->enablestats)) {
-    print_error('statsdisable', 'error');
+    throw new \moodle_exception('statsdisable', 'error');
 }
 
 $statsstatus = stats_check_uptodate($course->id);
@@ -119,7 +119,8 @@
 $timeoptions = stats_get_time_options($now,$lastweekend,$lastmonthend,$earliestday,$earliestweek,$earliestmonth);
 
 if (empty($timeoptions)) {
-    print_error('nostatstodisplay', '', $CFG->wwwroot.'/course/user.php?id='.$course->id.'&user='.$user->id.'&mode=outline');
+    throw new \moodle_exception('nostatstodisplay', '',
+        $CFG->wwwroot.'/course/user.php?id='.$course->id.'&user='.$user->id.'&mode=outline');
 }
 
 // use the earliest.
@@ -159,7 +160,8 @@
 $stats = $DB->get_records_sql($sql, $params);
 
 if (empty($stats)) {
-    print_error('nostatstodisplay', '', $CFG->wwwroot.'/course/user.php?id='.$course->id.'&user='.$user->id.'&mode=outline');
+    throw new \moodle_exception('nostatstodisplay', '',
+        $CFG->wwwroot.'/course/user.php?id='.$course->id.'&user='.$user->id.'&mode=outline');
 }
 
 report_stats_print_chart($course->id, STATS_REPORT_USER_VIEW, $time, STATS_MODE_DETAILED, $user->id);
diff --git a/report/view.php b/report/view.php
index f8d768a96a827..265e2a9fb6a92 100644
--- a/report/view.php
+++ b/report/view.php
@@ -32,7 +32,7 @@
 
 // Basic access checks.
 if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 require_login($course);
 
diff --git a/repository/draftfiles_ajax.php b/repository/draftfiles_ajax.php
index 8f7a6af0492a1..78e200d22ad72 100644
--- a/repository/draftfiles_ajax.php
+++ b/repository/draftfiles_ajax.php
@@ -33,7 +33,7 @@
 $PAGE->set_context(context_system::instance());
 require_login();
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 require_sesskey();
 
diff --git a/repository/draftfiles_manager.php b/repository/draftfiles_manager.php
index 29cfae24323d4..99019a7df2f06 100644
--- a/repository/draftfiles_manager.php
+++ b/repository/draftfiles_manager.php
@@ -144,7 +144,7 @@
         $fileurl = moodle_url::make_draftfile_url($newdraftitemid, '/', $filename)->out();
         header('Location: ' . $fileurl);
     } else {
-        print_error('cannotdownloaddir', 'repository');
+        throw new \moodle_exception('cannotdownloaddir', 'repository');
     }
     break;
 
diff --git a/repository/filepicker.php b/repository/filepicker.php
index 9ea912e2b80f8..09c1d41ea99ba 100644
--- a/repository/filepicker.php
+++ b/repository/filepicker.php
@@ -73,7 +73,7 @@
 
 $PAGE->set_context($user_context);
 if (!$course = $DB->get_record('course', array('id'=>$courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 $PAGE->set_course($course);
 
@@ -281,7 +281,7 @@
 case 'download':
     // Check that user has permission to access this file
     if (!$repo->file_is_accessible($fileurl)) {
-        print_error('storedfilecannotread');
+        throw new \moodle_exception('storedfilecannotread');
     }
     $record = new stdClass();
     $reference = $repo->get_file_reference($fileurl);
@@ -327,17 +327,17 @@
             $filesize = filesize($thefile['path']);
             if ($maxbytes != -1 && $filesize>$maxbytes) {
                 unlink($thefile['path']);
-                print_error('maxbytes');
+                throw new \moodle_exception('maxbytes');
             }
             // Ensure the file will not make the area exceed its size limit.
             if (file_is_draft_area_limit_reached($record->itemid, $areamaxbytes, $filesize)) {
                 unlink($thefile['path']);
-                print_error('maxareabytes');
+                throw new \moodle_exception('maxareabytes');
             }
             // Ensure the user does not upload too many draft files in a short period.
             if (file_is_draft_areas_limit_reached($USER->id)) {
                 unlink($thefile['path']);
-                print_error('maxdraftitemids');
+                throw new \moodle_exception('maxdraftitemids');
             }
             try {
                 $info = repository::move_to_filepool($thefile['path'], $record);
@@ -349,7 +349,7 @@
                 throw $e;
             }
         } else {
-            print_error('cannotdownload', 'repository');
+            throw new \moodle_exception('cannotdownload', 'repository');
         }
     }
 
diff --git a/repository/manage_instances.php b/repository/manage_instances.php
index 34a30f94bebae..631127feb1131 100644
--- a/repository/manage_instances.php
+++ b/repository/manage_instances.php
@@ -76,7 +76,7 @@
     $pagename = get_string("repositorycourse",'repository');
 
     if ( !$course = $DB->get_record('course', array('id'=>$context->instanceid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
     require_login($course, false);
     // If the user is allowed to edit this course, he's allowed to edit list of repository instances
@@ -88,11 +88,11 @@
     $pagename = get_string('manageinstances', 'repository');
     //is the user looking at its own repository instances
     if ($USER->id != $context->instanceid){
-        print_error('notyourinstances', 'repository');
+        throw new \moodle_exception('notyourinstances', 'repository');
     }
     $user = $USER;
 } else {
-    print_error('invalidcontext');
+    throw new \moodle_exception('invalidcontext');
 }
 
 /// Security: we cannot perform any action if the type is not visible or if the context has been disabled
@@ -108,13 +108,13 @@
 
 if (isset($type)) {
     if (!$type->get_visible()) {
-        print_error('typenotvisible', 'repository', $baseurl);
+        throw new \moodle_exception('typenotvisible', 'repository', $baseurl);
     }
     // Prevents the user from creating/editing an instance if the repository is not visible in
     // this context OR if the user does not have the capability to view this repository in this context.
     $canviewrepository = has_capability('repository/'.$type->get_typename().':view', $context);
     if (!$type->get_contextvisibility($context) || !$canviewrepository) {
-        print_error('usercontextrepositorydisabled', 'repository', $baseurl);
+        throw new \moodle_exception('usercontextrepositorydisabled', 'repository', $baseurl);
     }
 }
 
@@ -123,7 +123,7 @@
     // The context passed MUST match the context of the repository. And as both have to be
     // similar, this also ensures that the context is either a user one, or a course one.
     if ($instance->instance->contextid != $context->id) {
-        print_error('invalidcontext');
+        throw new \moodle_exception('invalidcontext');
     }
     if ($instance->readonly) {
         // Cannot edit, or delete a readonly instance.
@@ -169,7 +169,7 @@
 
     } else if ($fromform = $mform->get_data()){
         if (!confirm_sesskey()) {
-            print_error('confirmsesskeybad', '', $baseurl);
+            throw new \moodle_exception('confirmsesskeybad', '', $baseurl);
         }
         if ($edit) {
             $settings = array();
@@ -186,7 +186,7 @@
             $savedstr = get_string('configsaved', 'repository');
             redirect($baseurl);
         } else {
-            print_error('instancenotsaved', 'repository', $baseurl);
+            throw new \moodle_exception('instancenotsaved', 'repository', $baseurl);
         }
         exit;
     } else {     // Display the form
@@ -200,13 +200,13 @@
 } else if (!empty($delete)) {
     if ($sure) {
         if (!confirm_sesskey()) {
-            print_error('confirmsesskeybad', '', $baseurl);
+            throw new \moodle_exception('confirmsesskeybad', '', $baseurl);
         }
         if ($instance->delete()) {
             $deletedstr = get_string('instancedeleted', 'repository');
             redirect($baseurl, $deletedstr, 3);
         } else {
-            print_error('instancenotdeleted', 'repository', $baseurl);
+            throw new \moodle_exception('instancenotdeleted', 'repository', $baseurl);
         }
         exit;
     }
diff --git a/repository/repository_callback.php b/repository/repository_callback.php
index 19cb9fa7aa3da..5cc9e64724d4b 100644
--- a/repository/repository_callback.php
+++ b/repository/repository_callback.php
@@ -55,7 +55,7 @@
     $classname = 'repository_' . $type;
     $repo = new $classname($repo_id, $repository->contextid, array('type'=>$type));
 } else {
-    print_error('invalidplugin', 'repository', $type);
+    throw new \moodle_exception('invalidplugin', 'repository', $type);
 }
 
 // post callback
diff --git a/tag/edit.php b/tag/edit.php
index cbd53134fc95f..b360d3212d8e5 100644
--- a/tag/edit.php
+++ b/tag/edit.php
@@ -33,7 +33,7 @@
 require_login();
 
 if (empty($CFG->usetags)) {
-    print_error('tagsaredisabled', 'tag');
+    throw new \moodle_exception('tagsaredisabled', 'tag');
 }
 
 //Editing a tag requires moodle/tag:edit capability
diff --git a/tag/index.php b/tag/index.php
index 03d6b4d7a2a8d..6ef8fc7b04608 100644
--- a/tag/index.php
+++ b/tag/index.php
@@ -29,7 +29,7 @@
 require_login();
 
 if (empty($CFG->usetags)) {
-    print_error('tagsaredisabled', 'tag');
+    throw new \moodle_exception('tagsaredisabled', 'tag');
 }
 
 $tagid       = optional_param('id', 0, PARAM_INT); // tag id
diff --git a/tag/manage.php b/tag/manage.php
index c8dfe39f705f3..e4165a8095590 100644
--- a/tag/manage.php
+++ b/tag/manage.php
@@ -57,7 +57,7 @@
 admin_externalpage_setup('managetags', '', $params, '', array('pagelayout' => 'report'));
 
 if (empty($CFG->usetags)) {
-    print_error('tagsaredisabled', 'tag');
+    throw new \moodle_exception('tagsaredisabled', 'tag');
 }
 
 $tagobject = null;
diff --git a/tag/search.php b/tag/search.php
index 3526fa973f13d..eb0e915e9a88e 100644
--- a/tag/search.php
+++ b/tag/search.php
@@ -26,7 +26,7 @@
 require_login();
 
 if (empty($CFG->usetags)) {
-    print_error('tagsaredisabled', 'tag');
+    throw new \moodle_exception('tagsaredisabled', 'tag');
 }
 
 $query     = optional_param('query', '', PARAM_RAW);
diff --git a/tag/user.php b/tag/user.php
index ffcbfb93a68df..50806ec1e6dcc 100644
--- a/tag/user.php
+++ b/tag/user.php
@@ -8,15 +8,15 @@
 require_login();
 
 if (empty($CFG->usetags)) {
-    print_error('tagdisabled');
+    throw new \moodle_exception('tagdisabled');
 }
 
 if (isguestuser()) {
-    print_error('noguest');
+    throw new \moodle_exception('noguest');
 }
 
 if (!confirm_sesskey()) {
-    print_error('sesskey');
+    throw new \moodle_exception('sesskey');
 }
 
 $usercontext = context_user::instance($USER->id);
@@ -24,7 +24,7 @@
 switch ($action) {
     case 'addinterest':
         if (!core_tag_tag::is_enabled('core', 'user')) {
-            print_error('tagdisabled');
+            throw new \moodle_exception('tagdisabled');
         }
         $tag = required_param('tag', PARAM_TAG);
         core_tag_tag::add_item_tag('core', 'user', $USER->id, $usercontext, $tag);
@@ -34,7 +34,7 @@
 
     case 'removeinterest':
         if (!core_tag_tag::is_enabled('core', 'user')) {
-            print_error('tagdisabled');
+            throw new \moodle_exception('tagdisabled');
         }
         $tag = required_param('tag', PARAM_TAG);
         core_tag_tag::remove_item_tag('core', 'user', $USER->id, $tag);
@@ -51,6 +51,6 @@
         break;
 
     default:
-        print_error('unknowaction');
+        throw new \moodle_exception('unknowaction');
         break;
 }
diff --git a/theme/index.php b/theme/index.php
index 93bf2d3ed6f20..65afd7e015d8d 100644
--- a/theme/index.php
+++ b/theme/index.php
@@ -37,7 +37,7 @@
     $devices = core_useragent::get_device_type_list();
     if (!in_array($device, $devices)) {
         // The provided device isn't a valid device throw an error.
-        print_error('invaliddevicetype');
+        throw new \moodle_exception('invaliddevicetype');
     }
 }
 
diff --git a/user/action_redir.php b/user/action_redir.php
index f5eb605375a6a..41beff00e91bb 100644
--- a/user/action_redir.php
+++ b/user/action_redir.php
@@ -35,11 +35,11 @@
 $actions = array('bulkchange.php');
 
 if (array_search($formaction, $actions) === false) {
-    print_error('unknownuseraction');
+    throw new \moodle_exception('unknownuseraction');
 }
 
 if (!confirm_sesskey()) {
-    print_error('confirmsesskeybad');
+    throw new \moodle_exception('confirmsesskeybad');
 }
 
 if ($formaction == 'bulkchange.php') {
@@ -182,14 +182,14 @@ function(stdClass $record, bool $supportshtml) use ($identityfields): stdClass {
             }
         }
         if (!$instance) {
-            print_error('errorwithbulkoperation', 'enrol');
+            throw new \moodle_exception('errorwithbulkoperation', 'enrol');
         }
 
         $manager = new course_enrolment_manager($PAGE, $course, $instance->id);
         $plugins = $manager->get_enrolment_plugins();
 
         if (!isset($plugins[$plugin])) {
-            print_error('errorwithbulkoperation', 'enrol');
+            throw new \moodle_exception('errorwithbulkoperation', 'enrol');
         }
 
         $plugin = $plugins[$plugin];
@@ -197,7 +197,7 @@ function(stdClass $record, bool $supportshtml) use ($identityfields): stdClass {
         $operations = $plugin->get_bulk_operations($manager);
 
         if (!isset($operations[$operationname])) {
-            print_error('errorwithbulkoperation', 'enrol');
+            throw new \moodle_exception('errorwithbulkoperation', 'enrol');
         }
         $operation = $operations[$operationname];
 
@@ -244,7 +244,7 @@ function(stdClass $record, bool $supportshtml) use ($identityfields): stdClass {
             if ($operation->process($manager, $users, new stdClass)) {
                 redirect($returnurl);
             } else {
-                print_error('errorwithbulkoperation', 'enrol');
+                throw new \moodle_exception('errorwithbulkoperation', 'enrol');
             }
         }
         // Check if the bulk operation has been cancelled.
diff --git a/user/edit.php b/user/edit.php
index be4f6e056ecc7..2a827d6500600 100644
--- a/user/edit.php
+++ b/user/edit.php
@@ -37,7 +37,7 @@
 $PAGE->set_url('/user/edit.php', array('course' => $course, 'id' => $userid));
 
 if (!$course = $DB->get_record('course', array('id' => $course))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 if ($course->id != SITEID) {
@@ -53,17 +53,17 @@
 
 // Guest can not edit.
 if (isguestuser()) {
-    print_error('guestnoeditprofile');
+    throw new \moodle_exception('guestnoeditprofile');
 }
 
 // The user profile we are editing.
 if (!$user = $DB->get_record('user', array('id' => $userid))) {
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 // Guest can not be edited.
 if (isguestuser($user)) {
-    print_error('guestnoeditprofile');
+    throw new \moodle_exception('guestnoeditprofile');
 }
 
 // User interests separated by commas.
@@ -75,7 +75,7 @@
 if (is_mnet_remote_user($user)) {
     if (user_not_fully_set_up($user, true)) {
         $hostwwwroot = $DB->get_field('mnet_host', 'wwwroot', array('id' => $user->mnethostid));
-        print_error('usernotfullysetup', 'mnet', '', $hostwwwroot);
+        throw new \moodle_exception('usernotfullysetup', 'mnet', '', $hostwwwroot);
     }
     redirect($CFG->wwwroot . "/user/view.php?course={$course->id}");
 }
@@ -84,7 +84,7 @@
 $userauth = get_auth_plugin($user->auth);
 
 if (!$userauth->can_edit_profile()) {
-    print_error('noprofileedit', 'auth');
+    throw new \moodle_exception('noprofileedit', 'auth');
 }
 
 if ($editurl = $userauth->edit_profile_url()) {
@@ -104,7 +104,7 @@
 if ($user->id == $USER->id) {
     // Editing own profile - require_login() MUST NOT be used here, it would result in infinite loop!
     if (!has_capability('moodle/user:editownprofile', $systemcontext)) {
-        print_error('cannotedityourprofile');
+        throw new \moodle_exception('cannotedityourprofile');
     }
 
 } else {
@@ -112,11 +112,11 @@
     require_capability('moodle/user:editprofile', $personalcontext);
     // No editing of guest user account.
     if (isguestuser($user->id)) {
-        print_error('guestnoeditprofileother');
+        throw new \moodle_exception('guestnoeditprofileother');
     }
     // No editing of primary admin!
     if (is_siteadmin($user) and !is_siteadmin($USER)) {  // Only admins may edit other admins.
-        print_error('useradmineditadmin');
+        throw new \moodle_exception('useradmineditadmin');
     }
 }
 
@@ -224,7 +224,7 @@
     // Pass a true old $user here.
     if (!$authplugin->user_update($user, $usernew)) {
         // Auth update failed.
-        print_error('cannotupdateprofile');
+        throw new \moodle_exception('cannotupdateprofile');
     }
 
     // Update user with new profile data.
diff --git a/user/editadvanced.php b/user/editadvanced.php
index 6ae2169abf1c4..3bc3e14f505c9 100644
--- a/user/editadvanced.php
+++ b/user/editadvanced.php
@@ -96,11 +96,11 @@
 }
 
 if ($user->id != $USER->id and is_siteadmin($user) and !is_siteadmin($USER)) {  // Only admins may edit other admins.
-    print_error('useradmineditadmin');
+    throw new \moodle_exception('useradmineditadmin');
 }
 
 if (isguestuser($user->id)) { // The real guest user can not be edited.
-    print_error('guestnoeditprofileother');
+    throw new \moodle_exception('guestnoeditprofileother');
 }
 
 if ($user->deleted) {
@@ -216,7 +216,7 @@
         // Pass a true old $user here.
         if (!$authplugin->user_update($user, $usernew)) {
             // Auth update failed.
-            print_error('cannotupdateuseronexauth', '', '', $user->auth);
+            throw new \moodle_exception('cannotupdateuseronexauth', '', '', $user->auth);
         }
         user_update_user($usernew, false, false);
 
@@ -224,7 +224,7 @@
         if (!empty($usernew->newpassword)) {
             if ($authplugin->can_change_password()) {
                 if (!$authplugin->user_update_password($usernew, $usernew->newpassword)) {
-                    print_error('cannotupdatepasswordonextauth', '', '', $usernew->auth);
+                    throw new \moodle_exception('cannotupdatepasswordonextauth', '', '', $usernew->auth);
                 }
                 unset_user_preference('create_password', $usernew); // Prevent cron from generating the password.
 
diff --git a/user/editlib.php b/user/editlib.php
index a88e0ac6556cd..92e829ef85733 100644
--- a/user/editlib.php
+++ b/user/editlib.php
@@ -48,11 +48,11 @@ function useredit_setup_preference_page($userid, $courseid) {
 
     // Guest can not edit.
     if (isguestuser()) {
-        print_error('guestnoeditprofile');
+        throw new \moodle_exception('guestnoeditprofile');
     }
 
     if (!$course = $DB->get_record('course', array('id' => $courseid))) {
-        print_error('invalidcourseid');
+        throw new \moodle_exception('invalidcourseid');
     }
 
     if ($course->id != SITEID) {
@@ -68,19 +68,19 @@ function useredit_setup_preference_page($userid, $courseid) {
 
     // The user profile we are editing.
     if (!$user = $DB->get_record('user', array('id' => $userid))) {
-        print_error('invaliduserid');
+        throw new \moodle_exception('invaliduserid');
     }
 
     // Guest can not be edited.
     if (isguestuser($user)) {
-        print_error('guestnoeditprofile');
+        throw new \moodle_exception('guestnoeditprofile');
     }
 
     // Remote users cannot be edited.
     if (is_mnet_remote_user($user)) {
         if (user_not_fully_set_up($user, false)) {
             $hostwwwroot = $DB->get_field('mnet_host', 'wwwroot', array('id' => $user->mnethostid));
-            print_error('usernotfullysetup', 'mnet', '', $hostwwwroot);
+            throw new \moodle_exception('usernotfullysetup', 'mnet', '', $hostwwwroot);
         }
         redirect($CFG->wwwroot . "/user/view.php?course={$course->id}");
     }
@@ -92,7 +92,7 @@ function useredit_setup_preference_page($userid, $courseid) {
     if ($user->id == $USER->id) {
         // Editing own profile - require_login() MUST NOT be used here, it would result in infinite loop!
         if (!has_capability('moodle/user:editownprofile', $systemcontext)) {
-            print_error('cannotedityourprofile');
+            throw new \moodle_exception('cannotedityourprofile');
         }
 
     } else {
@@ -101,7 +101,7 @@ function useredit_setup_preference_page($userid, $courseid) {
 
         // No editing of primary admin!
         if (is_siteadmin($user) and !is_siteadmin($USER)) {  // Only admins may edit other admins.
-            print_error('useradmineditadmin');
+            throw new \moodle_exception('useradmineditadmin');
         }
     }
 
diff --git a/user/emailupdate.php b/user/emailupdate.php
index 4080eada0ff09..0577c68a0a9ec 100644
--- a/user/emailupdate.php
+++ b/user/emailupdate.php
@@ -34,7 +34,7 @@
 $PAGE->set_context(context_system::instance());
 
 if (!$user = $DB->get_record('user', array('id' => $id))) {
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 $preferences = get_user_preferences(null, null, $user->id);
diff --git a/user/filters/lib.php b/user/filters/lib.php
index 9cfb1bb99be72..d960af8277e0e 100644
--- a/user/filters/lib.php
+++ b/user/filters/lib.php
@@ -330,7 +330,7 @@ public function user_filter_type($name, $label, $advanced) {
      * @return string the filtering condition or null if the filter is disabled
      */
     public function get_sql_filter($data) {
-        print_error('mustbeoveride', 'debug', '', 'get_sql_filter');
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'get_sql_filter');
     }
 
     /**
@@ -339,7 +339,7 @@ public function get_sql_filter($data) {
      * @return mixed array filter data or false when filter not set
      */
     public function check_data($formdata) {
-        print_error('mustbeoveride', 'debug', '', 'check_data');
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'check_data');
     }
 
     /**
@@ -347,7 +347,7 @@ public function check_data($formdata) {
      * @param moodleform $mform a MoodleForm object to setup
      */
     public function setupForm(&$mform) {
-        print_error('mustbeoveride', 'debug', '', 'setupForm');
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'setupForm');
     }
 
     /**
@@ -356,6 +356,6 @@ public function setupForm(&$mform) {
      * @return string active filter label
      */
     public function get_label($data) {
-        print_error('mustbeoveride', 'debug', '', 'get_label');
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'get_label');
     }
 }
diff --git a/user/grouppix.php b/user/grouppix.php
index 8a0a515807c26..10a2b9ef7c064 100644
--- a/user/grouppix.php
+++ b/user/grouppix.php
@@ -49,5 +49,5 @@
     send_file($pathname, $image);
 } else {
     header('HTTP/1.0 404 not found');
-    print_error('filenotfound', 'error'); // This is not displayed on IIS??
+    throw new \moodle_exception('filenotfound', 'error'); // This is not displayed on IIS??
 }
diff --git a/user/index.php b/user/index.php
index bdc1829f165b3..f4ae87deacafc 100644
--- a/user/index.php
+++ b/user/index.php
@@ -55,7 +55,7 @@
 if ($contextid) {
     $context = context::instance_by_id($contextid, MUST_EXIST);
     if ($context->contextlevel != CONTEXT_COURSE) {
-        print_error('invalidcontext');
+        throw new \moodle_exception('invalidcontext');
     }
     $course = $DB->get_record('course', array('id' => $context->instanceid), '*', MUST_EXIST);
 } else {
diff --git a/user/portfolio.php b/user/portfolio.php
index 4cd41825a420d..16446190c7c52 100644
--- a/user/portfolio.php
+++ b/user/portfolio.php
@@ -25,7 +25,7 @@
 require_once(__DIR__ . '/../config.php');
 
 if (empty($CFG->enableportfolios)) {
-    print_error('disabled', 'portfolio');
+    throw new \moodle_exception('disabled', 'portfolio');
 }
 
 require_once($CFG->libdir . '/portfoliolib.php');
@@ -41,7 +41,7 @@
     $url->param('config', $config);
 }
 if (! $course = $DB->get_record("course", array("id" => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 $user = $USER;
@@ -76,7 +76,7 @@
         exit;
     } else if ($fromform = $mform->get_data()) {
         if (!confirm_sesskey()) {
-            print_error('confirmsesskeybad', '', $baseurl);
+            throw new \moodle_exception('confirmsesskeybad', '', $baseurl);
         }
         // This branch is where you process validated data.
         $instance->set_user_config($fromform, $USER->id);
@@ -105,7 +105,7 @@
     echo html_writer::tag('p', $introstr);
 
     if (!$instances = portfolio_instances(true, false)) {
-        print_error('noinstances', 'portfolio', $CFG->wwwroot . '/user/view.php');
+        throw new \moodle_exception('noinstances', 'portfolio', $CFG->wwwroot . '/user/view.php');
     }
 
     $table = new html_table();
diff --git a/user/portfoliologs.php b/user/portfoliologs.php
index 7251b7d9f2752..9fdf613142a93 100644
--- a/user/portfoliologs.php
+++ b/user/portfoliologs.php
@@ -25,7 +25,7 @@
 require_once(__DIR__ . '/../config.php');
 
 if (empty($CFG->enableportfolios)) {
-    print_error('disabled', 'portfolio');
+    throw new \moodle_exception('disabled', 'portfolio');
 }
 
 require_once($CFG->libdir . '/portfoliolib.php');
@@ -36,7 +36,7 @@
 $perpage  = optional_param('perpage', 10, PARAM_INT);
 
 if (! $course = $DB->get_record("course", array("id" => $courseid))) {
-    print_error('invalidcourseid');
+    throw new \moodle_exception('invalidcourseid');
 }
 
 require_login($course, false);
diff --git a/user/profile.php b/user/profile.php
index 8af000e7140c6..93f53787f5adf 100644
--- a/user/profile.php
+++ b/user/profile.php
@@ -94,7 +94,7 @@
 
 // Get the profile page.  Should always return something unless the database is broken.
 if (!$currentpage = my_get_page($userid, MY_PAGE_PUBLIC)) {
-    print_error('mymoodlesetup');
+    throw new \moodle_exception('mymoodlesetup');
 }
 
 $PAGE->set_context($context);
@@ -140,7 +140,7 @@
     if ($reset !== null) {
         if (!is_null($userid)) {
             if (!$currentpage = my_reset_page($userid, MY_PAGE_PUBLIC, 'user-profile')) {
-                print_error('reseterror', 'my');
+                throw new \moodle_exception('reseterror', 'my');
             }
             redirect(new moodle_url('/user/profile.php', array('id' => $userid)));
         }
@@ -157,7 +157,7 @@
             // For the page to display properly with the user context header the page blocks need to
             // be copied over to the user context.
             if (!$currentpage = my_copy_page($userid, MY_PAGE_PUBLIC, 'user-profile')) {
-                print_error('mymoodlesetup');
+                throw new \moodle_exception('mymoodlesetup');
             }
             $PAGE->set_context($usercontext);
             $PAGE->set_subpage($currentpage->id);
diff --git a/user/profile/definelib.php b/user/profile/definelib.php
index bf57b78b74352..efd03c4d4dbaa 100644
--- a/user/profile/definelib.php
+++ b/user/profile/definelib.php
@@ -284,11 +284,11 @@ function profile_delete_category($id) {
 
     // Retrieve the category.
     if (!$category = $DB->get_record('user_info_category', array('id' => $id))) {
-        print_error('invalidcategoryid');
+        throw new \moodle_exception('invalidcategoryid');
     }
 
     if (!$categories = $DB->get_records('user_info_category', null, 'sortorder ASC')) {
-        print_error('nocate', 'debug');
+        throw new \moodle_exception('nocate', 'debug');
     }
 
     unset($categories[$category->id]);
@@ -343,7 +343,7 @@ function profile_delete_field($id) {
 
     // Remove any user data associated with this field.
     if (!$DB->delete_records('user_info_data', array('fieldid' => $id))) {
-        print_error('cannotdeletecustomfield');
+        throw new \moodle_exception('cannotdeletecustomfield');
     }
 
     // Note: Any availability conditions that depend on this field will remain,
diff --git a/user/profile/lib.php b/user/profile/lib.php
index cd450d5d6f125..d1a64098c98d9 100644
--- a/user/profile/lib.php
+++ b/user/profile/lib.php
@@ -133,7 +133,7 @@ public function profile_field_base($fieldid=0, $userid=0) {
      * @param MoodleQuickForm $mform instance of the moodleform class
      */
     public function edit_field_add($mform) {
-        print_error('mustbeoveride', 'debug', '', 'edit_field_add');
+        throw new \moodle_exception('mustbeoveride', 'debug', '', 'edit_field_add');
     }
 
     /**
diff --git a/user/profilesys.php b/user/profilesys.php
index 61e4512226988..3caabf6a1a467 100644
--- a/user/profilesys.php
+++ b/user/profilesys.php
@@ -53,7 +53,7 @@
 
 // Get the Public Profile page info.  Should always return something unless the database is broken.
 if (!$currentpage = my_get_page(null, MY_PAGE_PUBLIC)) {
-    print_error('publicprofilesetup');
+    throw new \moodle_exception('publicprofilesetup');
 }
 $PAGE->set_subpage($currentpage->id);
 
diff --git a/user/repository.php b/user/repository.php
index 1f69deed8f916..d398a8380c7d9 100644
--- a/user/repository.php
+++ b/user/repository.php
@@ -66,7 +66,7 @@
 $params['currentcontext'] = $PAGE->context;
 $params['userid']   = $USER->id;
 if (!$instances = repository::get_instances($params)) {
-    print_error('noinstances', 'repository', $CFG->wwwroot . '/user/view.php');
+    throw new \moodle_exception('noinstances', 'repository', $CFG->wwwroot . '/user/view.php');
 }
 
 $table = new html_table();
diff --git a/user/selector/search.php b/user/selector/search.php
index dea5d81c1d3c0..7adce0667fa5e 100644
--- a/user/selector/search.php
+++ b/user/selector/search.php
@@ -42,7 +42,7 @@
 // Get and validate the selectorid parameter.
 $selectorhash = required_param('selectorid', PARAM_ALPHANUM);
 if (!isset($USER->userselectors[$selectorhash])) {
-    print_error('unknownuserselector');
+    throw new \moodle_exception('unknownuserselector');
 }
 
 // Get the options.
diff --git a/user/view.php b/user/view.php
index 5ccfd8b439550..2390bc590225f 100644
--- a/user/view.php
+++ b/user/view.php
@@ -55,7 +55,7 @@
 // Check we are not trying to view guest's profile.
 if (isguestuser($user)) {
     // Can not view profile of guest - thre is nothing to see there.
-    print_error('invaliduserid');
+    throw new \moodle_exception('invaliduserid');
 }
 
 $PAGE->set_context($coursecontext);
@@ -128,7 +128,7 @@
 
     // Check to see if the user can see this user's profile.
     if (!user_can_view_profile($user, $course, $usercontext) && !$isparent) {
-        print_error('cannotviewprofile');
+        throw new \moodle_exception('cannotviewprofile');
     }
 
     if (!is_enrolled($coursecontext, $user->id)) {
diff --git a/webservice/recaptcha.php b/webservice/recaptcha.php
index 1e2ad7a29dfd2..da0bc5ee12298 100644
--- a/webservice/recaptcha.php
+++ b/webservice/recaptcha.php
@@ -73,7 +73,7 @@
     // To use reCAPTCHA you must have an API key.
     require_once($CFG->libdir . '/filelib.php');
     send_header_404();
-    print_error('cannotusepage2');
+    throw new \moodle_exception('cannotusepage2');
 }
 
 $output = <<<OET