Fatal error: Uncaught Error: Class "Symfony\Contracts\EventDispatcher\Event" not found in /srv/www/sites/public/starter-cms/vendor/symfony/mailer/Event/FailedMessageEvent.php:20 Stack trace: #0 {main} thrown in /srv/www/sites/public/starter-cms/vendor/symfony/mailer/Event/FailedMessageEvent.php on line 20