Fatal error: Uncaught Error: Interface "Symfony\Component\EventDispatcher\EventSubscriberInterface" not found in /home/www/drupal8/test/core/modules/config/tests/config_events_test/src/EventSubscriber.php:10 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/config/tests/config_events_test/src/EventSubscriber.php on line 10