Fatal error: Uncaught Error: Class "Symfony\Component\Mailer\Transport\RoundRobinTransport" not found in /home/zdpktgd/ptc/vendor.old/symfony/mailer/Transport/FailoverTransport.php:19 Stack trace: #0 {main} thrown in /home/zdpktgd/ptc/vendor.old/symfony/mailer/Transport/FailoverTransport.php on line 19