Fatal error: Uncaught Error: Class "Drupal\views\Plugin\views\row\RssPluginBase" not found in /home/www/drupal8/test/core/modules/aggregator/src/Plugin/views/row/Rss.php:19 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/modules/aggregator/src/Plugin/views/row/Rss.php on line 19