diff -r 259df9ecf9ca -r 35d6b9321ffd tests/wamp/.crossbar/config.json
--- a/tests/wamp/.crossbar/config.json	Mon Mar 19 12:18:07 2018 +0100
+++ b/tests/wamp/.crossbar/config.json	Tue Mar 27 10:11:04 2018 +0200
@@ -39,13 +39,15 @@
             "transports": [
                 {
                     "type": "websocket",
+                    "debug": true,
                     "endpoint": {
                         "type": "tcp",
                         "port": 8888
                     },
                     "url": "ws://127.0.0.1:8888/",
                     "serializers": [
-                        "msgpack"
+                        "msgpack",
+                        "json"
                     ]
                 }
             ]