Fatal error: Uncaught Error: Class "Drupal\system\FileDownloadController" not found in /home/www/drupal8/test/core/modules/image/src/Controller/ImageStyleDownloadController.php:21 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/image/src/Controller/ImageStyleDownloadController.php on line 21