Fatal error: Uncaught Error: Interface "Symfony\Component\EventDispatcher\EventSubscriberInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/EventSubscriber/OptionsRequestSubscriber.php:18
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/lib/Drupal/Core/EventSubscriber/OptionsRequestSubscriber.php on line 18