Fatal error: Uncaught Error: Interface "Drupal\Core\DependencyInjection\ServiceProviderInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/CoreServiceProvider.php:43 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/CoreServiceProvider.php on line 43