Fatal error: Uncaught Error: Interface 'Ratchet\RFC6455\Handshake\NegotiatorInterface' not found in /var/www/html/stz-api/vendor/ratchet/rfc6455/src/Handshake/ServerNegotiator.php:10 Stack trace: #0 {main} thrown in /var/www/html/stz-api/vendor/ratchet/rfc6455/src/Handshake/ServerNegotiator.php on line 10