Fatal error: Uncaught Error: Interface "Drupal\Core\Messenger\MessengerInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Messenger/Messenger.php:13
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Messenger/Messenger.php on line 13