Fatal error: Uncaught Error: Class "Drupal\Core\Cache\CacheCollector" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Utility/ThemeRegistry.php:19 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Utility/ThemeRegistry.php on line 19