Fatal error: Uncaught Error: Class 'Concrete\Core\Controller\Controller' not found in /srv/www/c5www/html/updates/concrete5-8.5.1/concrete/controllers/backend/file/thumbnailer.php:15 Stack trace: #0 {main} thrown in /srv/www/c5www/html/updates/concrete5-8.5.1/concrete/controllers/backend/file/thumbnailer.php on line 15