Fatal error: Uncaught Error: Class "Drupal\Core\Controller\ControllerBase" not found in /home/www/drupal8/test/core/modules/system/src/Controller/Http4xxController.php:10 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/system/src/Controller/Http4xxController.php on line 10