Fatal error: Uncaught Error: Class "Drupal\Core\Database\TransactionException" not found in /home/www/drupal8/test/core/lib/Drupal/Core/Database/TransactionExplicitCommitNotAllowedException.php:11
Stack trace:
#0 {main}
thrown in /home/www/drupal8/test/core/lib/Drupal/Core/Database/TransactionExplicitCommitNotAllowedException.php on line 11