Fatal error: Uncaught Error: Interface "Drupal\ckeditor\CKEditorPluginInterface" not found in /home/www/drupal8/test/core/modules/ckeditor/src/CKEditorPluginConfigurableInterface.php:24 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/ckeditor/src/CKEditorPluginConfigurableInterface.php on line 24