Fatal error: Uncaught Error: Class "Drupal\Core\Config\ConfigImportValidateEventSubscriberBase" not found in /home/www/drupal8/test/core/modules/config/src/ConfigSubscriber.php:12 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/config/src/ConfigSubscriber.php on line 12