Fatal error: Uncaught Error: Interface "Ratchet\Http\HttpServerInterface" not found in /users/energydata/www/volkszaehler.org/vendor/cboden/ratchet/src/Ratchet/Session/SessionProvider.php:17 Stack trace: #0 {main} thrown in /users/energydata/www/volkszaehler.org/vendor/cboden/ratchet/src/Ratchet/Session/SessionProvider.php on line 17