Fatal error: Uncaught Error: Class 'Magento\Framework\Serialize\Serializer\Json' not found in /home/esecureh/public_html/magdemo/vendor/magento/framework/Serialize/Serializer/JsonHexTag.php:21 Stack trace: #0 {main} thrown in /home/esecureh/public_html/magdemo/vendor/magento/framework/Serialize/Serializer/JsonHexTag.php on line 21