Fatal error: Uncaught Error: Interface "Ratchet\Session\Serialize\HandlerInterface" not found in /users/energydata/www/volkszaehler.org/vendor/cboden/ratchet/src/Ratchet/Session/Serialize/PhpHandler.php:4 Stack trace: #0 {main} thrown in /users/energydata/www/volkszaehler.org/vendor/cboden/ratchet/src/Ratchet/Session/Serialize/PhpHandler.php on line 4