Fatal error: Uncaught Error: Class "Magento\Backend\Block\Widget\Grid\Extended" not found in /var/www/magento/html/app/code/MGS/Lookbook/Block/Adminhtml/EditSlide/Tab/Items.php:8 Stack trace: #0 {main} thrown in /var/www/magento/html/app/code/MGS/Lookbook/Block/Adminhtml/EditSlide/Tab/Items.php on line 8