diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 2634621..d73dd5d 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -23,7 +23,7 @@ jobs:
 
     services:
       postgres:
-        image: postgres:10
+        image: postgres:12
         env:
           POSTGRES_USER: 'postgres'
           POSTGRES_HOST_AUTH_METHOD: 'trust'
diff --git a/db/install.xml b/db/install.xml
old mode 100644
new mode 100755
index de5c328..909c24a
--- a/db/install.xml
+++ b/db/install.xml
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8" ?>
-<XMLDB PATH="report/customsql/db" VERSION="20150630" COMMENT="XMLDB file for Moodle report/customsql"
+<XMLDB PATH="report/customsql/db" VERSION="20151013" COMMENT="XMLDB file for Moodle report/customsql"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:noNamespaceSchemaLocation="../../../lib/xmldb/xmldb.xsd"
 >
@@ -43,4 +43,4 @@
       </KEYS>
     </TABLE>
   </TABLES>
-</XMLDB>
+</XMLDB>
\ No newline at end of file
diff --git a/edit_form.php b/edit_form.php
index c380fef..889fdc2 100644
--- a/edit_form.php
+++ b/edit_form.php
@@ -150,6 +150,7 @@ public function definition() {
         $mform->disabledIf('singlerow', 'runable', 'eq', 'manual');
         $mform->disabledIf('at', 'runable', 'ne', 'daily');
         $mform->disabledIf('emailto', 'runable', 'eq', 'manual');
+        $mform->disabledIf('customdir', 'runable', 'eq', 'manual');
         $mform->disabledIf('emailwhat', 'runable', 'eq', 'manual');
 
         $this->add_action_buttons();
@@ -301,6 +302,16 @@ public function validation($data, $files) {
             }
         }
 
+        // Check that the custom directory is writable and a directory, if provided.
+        if (isset($data['customdir']) && !empty($data['customdir'])) {
+            if (!is_dir($data['customdir'])) {
+                $errors['customdir'] = get_string('notadirectory', 'report_customsql');
+            }
+            else if (!is_writable($data['customdir'])) {
+                $errors['customdir'] = get_string('directorynotwritable', 'report_customsql');
+            }
+        }
+
         return $errors;
     }
 }
diff --git a/lang/en/report_customsql.php b/lang/en/report_customsql.php
index e56d997..1e9d7b7 100644
--- a/lang/en/report_customsql.php
+++ b/lang/en/report_customsql.php
@@ -61,6 +61,7 @@
 $string['deletecategoryyesno'] = '<p>Are you really sure you want to delete this category? </p>';
 $string['deletereportx'] = 'Delete query \'{$a}\'';
 $string['description'] = 'Description';
+$string['directorynotwritable'] = 'The directory you provided is not writable.';
 $string['displayname'] = 'Query name';
 $string['displaynamex'] = 'Query name: {$a}';
 $string['displaynamerequired'] = 'You must enter a query name';
diff --git a/lib.php b/lib.php
index 21013e6..8294dbf 100644
--- a/lib.php
+++ b/lib.php
@@ -89,7 +89,7 @@ function report_customsql_pluginfile($course, $cm, $context, $filearea, $args, $
         if ($report->runable !== 'manual') {
             $runtime = $report->lastrun;
         }
-        $csvtimestamp = \report_customsql_generate_csv($report, $runtime);
+        $csvtimestamp = \report_customsql_generate_csv($report, $runtime, true);
     }
     list($csvfilename) = report_customsql_csv_filename($report, $csvtimestamp);
 
diff --git a/locallib.php b/locallib.php
index cd9fec4..423718b 100644
--- a/locallib.php
+++ b/locallib.php
@@ -96,7 +96,14 @@ function report_customsql_get_element_type($name) {
     return 'text';
 }
 
-function report_customsql_generate_csv($report, $timenow) {
+/**
+ * Generate customsql csv file.
+ *
+ * @param stdclass $report report record from customsql table.
+ * @param int $timetimenow unix timestamp - usually "now()"
+ * @param bool $returnheaderwhenempty if true, a CSV file with headers will always be generated, even if there are no results.
+ */
+function report_customsql_generate_csv($report, $timenow, $returnheaderwhenempty = false) {
     global $DB;
     $starttime = microtime(true);
 
@@ -104,6 +111,14 @@ function report_customsql_generate_csv($report, $timenow) {
 
     $queryparams = !empty($report->queryparams) ? unserialize($report->queryparams) : array();
     $querylimit  = $report->querylimit ?? get_config('report_customsql', 'querylimitdefault');
+    if ($returnheaderwhenempty) {
+        // We want the export to always generate a CSV file so we modify the query slightly
+        // to generate an extra "null" values row, so we can get the column names,
+        // then we ignore rows that contain null records in every row when generating the csv.
+        $sql = "SELECT subq.*
+                  FROM (SELECT 1) as ignoreme
+                  LEFT JOIN ($sql) as subq on true";
+    }
     // Query one extra row, so we can tell if we hit the limit.
     $rs = report_customsql_execute_query($sql, $queryparams, $querylimit + 1);
 
@@ -124,6 +139,11 @@ function report_customsql_generate_csv($report, $timenow) {
         }
 
         $data = get_object_vars($row);
+
+        if ($returnheaderwhenempty && array_unique(array_values($data)) === [null]) {
+            // This is a row with all null values - ignore it.
+            continue;
+        }
         foreach ($data as $name => $value) {
             if (report_customsql_get_element_type($name) == 'date_time_selector' &&
                     report_customsql_is_integer($value) && $value > 0) {
@@ -146,6 +166,7 @@ function report_customsql_generate_csv($report, $timenow) {
         fclose($handle);
     }
 
+
     // Update the execution time in the DB.
     $updaterecord = new stdClass();
     $updaterecord->id = $report->id;
diff --git a/tests/behat/behat_report_customsql.php b/tests/behat/behat_report_customsql.php
index 70a09cc..e02c23e 100644
--- a/tests/behat/behat_report_customsql.php
+++ b/tests/behat/behat_report_customsql.php
@@ -238,6 +238,28 @@ public function adhoc_database_queries_thinks_the_time_is($time) {
         set_config('behat_fixed_time', $value, 'report_customsql');
     }
 
+    /**
+     * Simulates downloading an empty report to ensure it shows table headers.
+     *
+     * For example:
+     * When downloading the empty custom sql report "Frog" it contains the headers "frogname,freddy"
+     *
+     * @Then /^downloading custom sql report "(?P<REPORT_NAME>[^"]*)" returns a file with headers "([^"]*)"$/
+     * @param string $reportname the name of the report to go to.
+     * @param string $headers the headers that shuold be returned.
+     */
+    public function downloading_custom_sql_report_x_returns_a_file_with_headers(string $reportname, string $headers) {
+        $report = $this->get_report_by_name($reportname);
+        $url = new \moodle_url('/pluginfile.php/1/'.'report_customsql'. '/'.'download'. '/'. $report->id, ['dataformat' => 'csv']);
+
+        $session = $this->getSession()->getCookie('MoodleSession');
+        $filecontent = trim(download_file_content($url, array('Cookie' => 'MoodleSession=' . $session)));
+        $filecontent = core_text::trim_utf8_bom($filecontent);
+        if ($filecontent != $headers) {
+            throw new \Behat\Mink\Exception\ExpectationException("File headers: $filecontent did not match expected: $headers", $this->getSession());
+        }
+    }
+
     /**
      * Find a report by name and get all the details.
      *
diff --git a/tests/behat/report_customsql.feature b/tests/behat/report_customsql.feature
index a831bd1..6c3e893 100644
--- a/tests/behat/report_customsql.feature
+++ b/tests/behat/report_customsql.feature
@@ -76,6 +76,13 @@ Feature: Ad-hoc database queries report
     And I view the "Test query" custom sql report
     Then I should see "This query did not return any data."
 
+  Scenario: Download an Ad-hoc database query that returns no data but includes headers
+    Given the following custom sql report exists:
+      | name     | Test query                               |
+      | querysql | SELECT * FROM {config} WHERE name = '-1' |
+    When I log in as "admin"
+    Then downloading custom sql report "Test query" returns a file with headers "id,name,value"
+
   Scenario: Create an Ad-hoc database queries category
     When I log in as "admin"
     And I navigate to "Reports > Ad-hoc database queries" in site administration
diff --git a/tests/privacy_test.php b/tests/privacy_test.php
index 4f2cb6e..9e50e35 100644
--- a/tests/privacy_test.php
+++ b/tests/privacy_test.php
@@ -81,7 +81,7 @@ public function test_export_user_data(): void {
         $subcontext = [
             get_string('privacy:metadata:reportcustomsqlqueries', 'report_customsql')
         ];
-        $data = $writer->get_data($subcontext);
+        $data = (array)$writer->get_data($subcontext);
         $this->assertEquals('Report of user 1', reset($data)['displayname']);
     }