Fatal error: Uncaught Error: Class 'Symfony\Component\HttpFoundation\Session\Storage\Handler\AbstractSessionHandler' not found in /home/soh-works/www/websoket-sample/vendor/symfony/http-foundation/Session/Storage/Handler/NullSessionHandler.php:19 Stack trace: #0 {main} thrown in /home/soh-works/www/websoket-sample/vendor/symfony/http-foundation/Session/Storage/Handler/NullSessionHandler.php on line 19