Fatal error: Uncaught Error: Class "Magento\Theme\Model\Design\Backend\File" not found in /var/www/magento/html/generated/code/Magento/Theme/Model/Design/Backend/File/Interceptor.php:7 Stack trace: #0 {main} thrown in /var/www/magento/html/generated/code/Magento/Theme/Model/Design/Backend/File/Interceptor.php on line 7