MC-42288: Coupon codes for existing cart price rule are not generated

- Block the coupon generates until cart price rule is saved with auto generate option enabled.

Author: Loganadhan P

app/code/Magento/SalesRule/Controller/Adminhtml/Promo/Quote/Generate.php

@@ -80,6 +80,10 @@ public function execute()
 
         if (!$rule->getId()) {
             $result['error'] = __('Rule is not defined');
+        } elseif ($rule->getCouponType() != \Magento\SalesRule\Model\Rule::COUPON_TYPE_AUTO
+            && !$rule->getUseAutoGeneration()) {
+            $result['error'] =
+                __('Rule is not saved with auto generate option enabled. Please save the rule and try again.');
         } else {
             try {
                 $data = $this->getRequest()->getParams();

app/code/Magento/SalesRule/i18n/en_US.csv

@@ -164,3 +164,4 @@ Apply,Apply
 "Apply to Shipping Amount","Apply to Shipping Amount"
 "Discard subsequent rules","Discard subsequent rules"
 "Default Rule Label for All Store Views","Default Rule Label for All Store Views"
+"Rule is not saved with auto generate option enabled. Please save the rule and try again.", "Rule is not saved with auto generate option enabled. Please save the rule and try again."