Fatal error: Uncaught Error: Class "Drupal\Core\Render\MainContent\DialogRenderer" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Render/MainContent/OffCanvasRenderer.php:17 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Render/MainContent/OffCanvasRenderer.php on line 17