added UpdateHandlerPlugin for tierprice issue

Author: zeel1012

app/code/Magento/Catalog/Model/Product/Attribute/Backend/TierPrice/UpdateHandler.php

@@ -15,7 +15,6 @@
 use Magento\Customer\Api\GroupManagementInterface;
 use Magento\Framework\EntityManager\MetadataPool;
 use Magento\Catalog\Model\ResourceModel\Product\Attribute\Backend\Tierprice;
-use Magento\ConfigurableProduct\Model\Product\Type\Configurable;
 
 /**
  * Process tier price data for handled existing product.
@@ -85,10 +84,6 @@ public function execute($entity, $arguments = [])
     {
         $attribute = $this->attributeRepository->get('tier_price');
         $priceRows = $entity->getData($attribute->getName());
-        $origPrices = $entity->getOrigData($attribute->getName());
-        if ($entity->getTypeId() === Configurable::TYPE_CODE && null !== $origPrices) {
-            $priceRows = [];
-        }
         if (null !== $priceRows) {
             if (!is_array($priceRows)) {
                 throw new \Magento\Framework\Exception\InputException(
@@ -101,6 +96,7 @@ public function execute($entity, $arguments = [])
             $productId = (int)$entity->getData($identifierField);
 
             // prepare original data to compare
+            $origPrices = $entity->getOrigData($attribute->getName());
             $old = $this->prepareOldTierPriceToCompare($origPrices);
             // prepare data for save
             $new = $this->prepareNewDataForSave($priceRows, $isGlobal);
@@ -266,4 +262,4 @@ private function prepareNewDataForSave(array $priceRows, bool $isGlobal = true):
 
         return $new;
     }
-}
+}

app/code/Magento/ConfigurableProduct/Plugin/Catalog/Model/Product/Attribute/Backend/TierPrice/UpdateHandlerPlugin.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace Magento\ConfigurableProduct\Plugin\Catalog\Model\Product\Attribute\Backend\TierPrice;
+
+use Magento\Catalog\Api\ProductAttributeRepositoryInterface;
+use Magento\Catalog\Model\Product\Attribute\Backend\TierPrice\UpdateHandler;
+use Magento\ConfigurableProduct\Model\Product\Type\Configurable;
+
+class UpdateHandlerPlugin
+{
+    /**
+     * @var ProductAttributeRepositoryInterface
+     */
+    private $attributeRepository;
+
+    /**
+     * @param ProductAttributeRepositoryInterface $attributeRepository
+     */
+    public function __construct(
+        ProductAttributeRepositoryInterface $attributeRepository
+    ) {
+        $this->attributeRepository = $attributeRepository;
+    }
+
+    /**
+     * @param UpdateHandler $subject
+     * @param mixed $entity
+     * @param array $arguments
+     * @return array
+     */
+    public function beforeExecute(UpdateHandler $subject, $entity, $arguments = [])
+    {
+        $attribute = $this->attributeRepository->get('tier_price');
+        $origPrices = $entity->getOrigData($attribute->getName());
+        
+        if ($entity->getTypeId() === Configurable::TYPE_CODE && $origPrices !== null) {
+            $entity->setData($attribute->getName(), []);
+        }
+
+        return [$entity, $arguments];
+    }
+}

app/code/Magento/ConfigurableProduct/etc/di.xml

@@ -288,4 +288,7 @@
     <type name="Magento\CatalogInventory\Model\ResourceModel\Stock\Item">
         <plugin name="updateStockChangedAuto" type="Magento\ConfigurableProduct\Model\Plugin\UpdateStockChangedAuto" />
     </type>
+    <type name="Magento\Catalog\Model\Product\Attribute\Backend\TierPrice\UpdateHandler">
+        <plugin name="tier_price_update_handler_plugin" type="Magento\ConfigurableProduct\Plugin\Catalog\Model\Product\Attribute\Backend\TierPrice\UpdateHandlerPlugin" sortOrder="10" disabled="false"/>
+    </type>
 </config>