Fatal error: Uncaught Error: Interface "Drupal\Core\Config\ConfigInstallerInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Config/ConfigInstaller.php:9 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Config/ConfigInstaller.php on line 9