MAGETWO-30913: Error when trying to apply coupon code in backend reorder after unchecking the discount apply checkbox

Author: Olexandr Lysenko

app/code/Magento/Sales/Controller/Adminhtml/Order/Create.php

@@ -270,16 +270,33 @@ protected function _processActionData($action = null)
         if (isset($data) && isset($data['coupon']['code'])) {
             $couponCode = trim($data['coupon']['code']);
         }
+
         if (!empty($couponCode)) {
-            if ($this->_getQuote()->getCouponCode() !== $couponCode) {
+            $isApplyDiscount = false;
+            foreach ($this->_getQuote()->getAllItems() as $item) {
+                if ($item->getIsApplyDiscount() === true) {
+                    $isApplyDiscount = true;
+                    break;
+                }
+            }
+            if (!$isApplyDiscount) {
                 $this->messageManager->addError(
                     __(
-                        '"%1" coupon code is not valid.',
+                        '"%1" coupon code for item(s) selected do not apply discount',
                         $this->_objectManager->get('Magento\Framework\Escaper')->escapeHtml($couponCode)
                     )
                 );
             } else {
-                $this->messageManager->addSuccess(__('The coupon code has been accepted.'));
+                if ($this->_getQuote()->getCouponCode() !== $couponCode) {
+                    $this->messageManager->addError(
+                        __(
+                            '"%1" coupon code is not valid.',
+                            $this->_objectManager->get('Magento\Framework\Escaper')->escapeHtml($couponCode)
+                        )
+                    );
+                } else {
+                    $this->messageManager->addSuccess(__('The coupon code has been accepted.'));
+                }
             }
         }
 

app/code/Magento/SalesRule/Model/Quote/Discount.php

@@ -87,6 +87,7 @@ public function collect(Address $address)
         foreach ($items as $item) {
             if ($item->getNoDiscount() || !$this->_calculator->canApplyDiscount($item)) {
                 $item->setDiscountAmount(0);
+                $item->setIsApplyDiscount(false);
                 $item->setBaseDiscountAmount(0);
 
                 // ensure my children are zeroed out
@@ -119,6 +120,7 @@ public function collect(Address $address)
                 $this->_calculator->process($item);
                 $this->_aggregateItemDiscount($item);
             }
+            $item->setIsApplyDiscount(true);
         }
 
         /**