Fatal error: Uncaught Error: Interface "Drupal\Core\Render\MainContent\MainContentRendererInterface" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Render/MainContent/AjaxRenderer.php:16
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Render/MainContent/AjaxRenderer.php on line 16