Fatal error: Uncaught Error: Class "Drupal\Core\Updater\UpdaterException" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Updater/UpdaterFileTransferException.php:14 Stack trace: #0 {main} thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Updater/UpdaterFileTransferException.php on line 14