Fatal error: Uncaught Error: Class "Drupal\file\Plugin\Field\FieldWidget\FileWidget" not found in /home/www/drupal8/test/core/modules/image/src/Plugin/Field/FieldWidget/ImageWidget.php:26 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/image/src/Plugin/Field/FieldWidget/ImageWidget.php on line 26