diff --git a/data/class/SC_Fpdf.php b/data/class/SC_Fpdf.php
index ca2b5bb3a7..d0ea777986 100644
--- a/data/class/SC_Fpdf.php
+++ b/data/class/SC_Fpdf.php
@@ -236,39 +236,42 @@ private function setOrderData()
 
         $arrTaxableTotal = [];
         $defaultTaxRule = SC_Helper_TaxRule_Ex::getTaxRule();
-        // 購入商品情報
-        for ($i = 0; $i < count($this->arrDisp['quantity']); $i++) {
-            // 購入数量
-            $data[0] = $this->arrDisp['quantity'][$i];
-
-            // 税込金額（単価）
-            $data[1] = $this->arrDisp['price'][$i] + SC_Helper_TaxRule_Ex::calcTax($this->arrDisp['price'][$i], $this->arrDisp['tax_rate'][$i], $this->arrDisp['tax_rule'][$i]);
-
-            // 小計（商品毎）
-            $data[2] = $data[0] * $data[1];
-
-            $arrOrder[$i][0] = $this->arrDisp['product_name'][$i].' / ';
-            $arrOrder[$i][0] .= $this->arrDisp['product_code'][$i].' / ';
-            if ($this->arrDisp['classcategory_name1'][$i]) {
-                $arrOrder[$i][0] .= ' [ '.$this->arrDisp['classcategory_name1'][$i];
-                if ($this->arrDisp['classcategory_name2'][$i] == '') {
-                    $arrOrder[$i][0] .= ' ]';
-                } else {
-                    $arrOrder[$i][0] .= ' * '.$this->arrDisp['classcategory_name2'][$i].' ]';
+        $i = 0;
+        // 受注明細情報
+        if (isset($this->arrDisp['quantity']) && is_array($this->arrDisp['quantity'])) {
+            for (; $i < count($this->arrDisp['quantity']); $i++) {
+                // 購入数量
+                $data[0] = $this->arrDisp['quantity'][$i];
+
+                // 税込金額（単価）
+                $data[1] = $this->arrDisp['price'][$i] + SC_Helper_TaxRule_Ex::calcTax($this->arrDisp['price'][$i], $this->arrDisp['tax_rate'][$i], $this->arrDisp['tax_rule'][$i]);
+
+                // 小計（商品毎）
+                $data[2] = $data[0] * $data[1];
+
+                $arrOrder[$i][0] = $this->arrDisp['product_name'][$i].' / ';
+                $arrOrder[$i][0] .= $this->arrDisp['product_code'][$i].' / ';
+                if ($this->arrDisp['classcategory_name1'][$i]) {
+                    $arrOrder[$i][0] .= ' [ '.$this->arrDisp['classcategory_name1'][$i];
+                    if ($this->arrDisp['classcategory_name2'][$i] == '') {
+                        $arrOrder[$i][0] .= ' ]';
+                    } else {
+                        $arrOrder[$i][0] .= ' * '.$this->arrDisp['classcategory_name2'][$i].' ]';
+                    }
                 }
-            }
 
-            // 標準税率より低い税率は軽減税率として※を付与
-            if ($this->arrDisp['tax_rate'][$i] < $defaultTaxRule['tax_rate']) {
-                $arrOrder[$i][0] .= ' ※';
-            }
-            $arrOrder[$i][1] = number_format($data[0]);
-            $arrOrder[$i][2] = number_format($data[1]).$monetary_unit;
-            $arrOrder[$i][3] = number_format($data[2]).$monetary_unit;
-            if (array_key_exists($this->arrDisp['tax_rate'][$i], $arrTaxableTotal) === false) {
-                $arrTaxableTotal[$this->arrDisp['tax_rate'][$i]] = 0;
+                // 標準税率より低い税率は軽減税率として※を付与
+                if ($this->arrDisp['tax_rate'][$i] < $defaultTaxRule['tax_rate']) {
+                    $arrOrder[$i][0] .= ' ※';
+                }
+                $arrOrder[$i][1] = number_format($data[0]);
+                $arrOrder[$i][2] = number_format($data[1]).$monetary_unit;
+                $arrOrder[$i][3] = number_format($data[2]).$monetary_unit;
+                if (array_key_exists($this->arrDisp['tax_rate'][$i], $arrTaxableTotal) === false) {
+                    $arrTaxableTotal[$this->arrDisp['tax_rate'][$i]] = 0;
+                }
+                $arrTaxableTotal[$this->arrDisp['tax_rate'][$i]] += $data[2];
             }
-            $arrTaxableTotal[$this->arrDisp['tax_rate'][$i]] += $data[2];
         }
 
         $arrOrder[$i][0] = '';
diff --git a/data/class/pages/admin/order/LC_Page_Admin_Order_Edit.php b/data/class/pages/admin/order/LC_Page_Admin_Order_Edit.php
index 8676d9a348..518119e9ff 100644
--- a/data/class/pages/admin/order/LC_Page_Admin_Order_Edit.php
+++ b/data/class/pages/admin/order/LC_Page_Admin_Order_Edit.php
@@ -692,7 +692,7 @@ public function lfCheckError(&$objFormParam)
 
         $arrErr = [];
         $arrErrTemp = $objFormParam->checkError();
-        $arrErrDate = [];
+        $arrErrDate = ['shipping_date_year' => []];
         foreach ($arrValues['shipping_date_year'] as $key_index => $year) {
             $month = $arrValues['shipping_date_month'][$key_index];
             $day = $arrValues['shipping_date_day'][$key_index];
@@ -702,7 +702,7 @@ public function lfCheckError(&$objFormParam)
                 'shipping_date_day' => $day,
             ]);
             $objError->doFunc(['お届け日', 'shipping_date_year', 'shipping_date_month', 'shipping_date_day'], ['CHECK_DATE']);
-            $arrErrDate['shipping_date_year'][$key_index] = $objError->arrErr['shipping_date_year'];
+            $arrErrDate['shipping_date_year'][$key_index] = isset($objError->arrErr['shipping_date_year']) ? $objError->arrErr['shipping_date_year'] : '';
         }
         $arrErrTemp = array_merge($arrErrTemp, $arrErrDate);
 
@@ -717,7 +717,10 @@ public function lfCheckError(&$objFormParam)
         ]);
         $objError->doFunc(['生年月日', 'order_birth_year', 'order_birth_month', 'order_birth_day'],
             ['CHECK_BIRTHDAY']);
-        $arrErrTemp['order_birth_year'] = $objError->arrErr['order_birth_year'];
+        if (!isset($arrErrTemp['order_birth_year'])) {
+            $arrErrTemp['order_birth_year'] = '';
+        }
+        $arrErrTemp['order_birth_year'] = isset($objError->arrErr['order_birth_year']) ? $objError->arrErr['order_birth_year'] : '';
 
         // 商品の種類数
         $max = count($arrValues['quantity']);
@@ -907,7 +910,7 @@ public function doRegister($order_id, &$objPurchase, &$objFormParam, &$message,
             $arrShippingValues[$shipping_index]['deliv_id'] = $objFormParam->getValue('deliv_id');
 
             // お届け時間名称を取得
-            $arrShippingValues[$shipping_index]['shipping_time'] = $arrDelivTime[$arrShipping['time_id']];
+            $arrShippingValues[$shipping_index]['shipping_time'] = $arrDelivTime[$arrShipping['time_id']] ?? '';
 
             // 複数配送の場合は配送商品を登録
             if (!SC_Utils_Ex::isBlank($arrAllShipmentItem)) {
@@ -1068,7 +1071,7 @@ public function shipmentAddProduct(&$objFormParam, $add_product_class_id)
         // 届け先に選択済みの商品がある場合
         $arrShipmentProducts = $this->getShipmentProducts($objFormParam);
 
-        if ($arrShipmentProducts['shipment_product_class_id'] && in_array($add_product_class_id, $arrShipmentProducts['shipment_product_class_id'][$select_shipping_id])) {
+        if ($arrShipmentProducts['shipment_product_class_id'] && in_array($add_product_class_id, $arrShipmentProducts['shipment_product_class_id'][$select_shipping_id] ?? [])) {
             foreach ($arrShipmentProducts['shipment_product_class_id'][$select_shipping_id] as $relation_index => $shipment_product_class_id) {
                 if ($shipment_product_class_id == $add_product_class_id) {
                     $arrShipmentProducts['shipment_quantity'][$select_shipping_id][$relation_index]++;
@@ -1229,9 +1232,14 @@ public function setProductsQuantity(&$objFormParam)
             $arrUpdateQuantity = [];
             foreach ($arrShipmentsItems as $arritems) {
                 foreach ($arritems['shipment_product_class_id'] as $relation_index => $shipment_product_class_id) {
+                    if (!isset($arrUpdateQuantity[$shipment_product_class_id])) {
+                        $arrUpdateQuantity[$shipment_product_class_id] = 0;
+                    }
                     // XXX 空文字が入ってくる場合があるので数値へキャストする
                     // きちんとエラーハンドリングすべきだが応急処置
-                    $arrUpdateQuantity[$shipment_product_class_id] += (int) $arritems['shipment_quantity'][$relation_index];
+                    if (is_numeric($arritems['shipment_quantity'][$relation_index])) {
+                        $arrUpdateQuantity[$shipment_product_class_id] += (int) $arritems['shipment_quantity'][$relation_index];
+                    }
                 }
             }
 
@@ -1321,11 +1329,11 @@ public function checkInsertOrderProducts(&$objFormParam, $arrProductClassIds, $i
             $arrAddProducts = [];
             $arrTax = SC_Helper_TaxRule_Ex::getTaxRule($arrAddProductInfo['product_id']);
 
-            $arrAddProductInfo['product_name'] = ($arrAddProductInfo['product_name'])
+            $arrAddProductInfo['product_name'] = isset($arrAddProductInfo['product_name'])
                 ? $arrAddProductInfo['product_name']
                 : $arrAddProductInfo['name'];
 
-            $arrAddProductInfo['price'] = ($arrAddProductInfo['price'])
+            $arrAddProductInfo['price'] = isset($arrAddProductInfo['price'])
                 ? $arrAddProductInfo['price']
                 : $arrAddProductInfo['price02'];
 
diff --git a/data/class/pages/admin/order/LC_Page_Admin_Order_ProductSelect.php b/data/class/pages/admin/order/LC_Page_Admin_Order_ProductSelect.php
index 10d90e1696..7b8f0b1553 100644
--- a/data/class/pages/admin/order/LC_Page_Admin_Order_ProductSelect.php
+++ b/data/class/pages/admin/order/LC_Page_Admin_Order_ProductSelect.php
@@ -89,7 +89,7 @@ public function action()
 
                 // ぶった斬りポイント==================================================================
                 // ページ送りの処理
-                $page_max = SC_Utils_Ex::sfGetSearchPageMax($_POST['search_page_max']);
+                $page_max = SC_Utils_Ex::sfGetSearchPageMax($_POST['search_page_max'] ?? 0);
 
                 // ページ送りの取得
                 $objNavi = new SC_PageNavi_Ex($_POST['search_pageno'], $this->tpl_linemax, $page_max, 'eccube.moveSearchPage', NAVI_PMAX);