MAGETWO-70741: An error occurs on attempt to add related product to configurable one

Author: Andrei Malets

app/code/Magento/Eav/Model/Entity/AttributeLoader.php

@@ -63,6 +63,9 @@ public function loadAllAttributes(AbstractEntity $resource, DataObject $object =
          * Check and init default attributes
          */
         $defaultAttributesCodes = array_diff($resource->getDefaultAttributes(), $attributeCodes);
+
+        $resource->unsetAttributes();
+
         foreach ($defaultAttributesCodes as $attributeCode) {
             $resource->addAttribute($this->_getDefaultAttribute($resource, $attributeCode));
         }

dev/tests/integration/testsuite/Magento/Catalog/Controller/Adminhtml/CategoryTest.php

@@ -339,7 +339,7 @@ public function testSaveActionCategoryWithDangerRequest()
         );
         $this->dispatch('backend/catalog/category/save');
         $this->assertSessionMessages(
-            $this->equalTo(['The value of attribute "is_active" must be set']),
+            $this->equalTo(['The value of attribute "name" must be set']),
             \Magento\Framework\Message\MessageInterface::TYPE_ERROR
         );
     }