Fatal error: Uncaught Error: Class "Symfony\Component\DependencyInjection\Dumper\Dumper" not found in /home/www/drupal8/test/core/lib/Drupal/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumper.php:36 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Component/DependencyInjection/Dumper/OptimizedPhpArrayDumper.php on line 36