BadYieldError: yielded unkown object None on connection

[Ishadijcks]

I run the following command on my robot: roslaunch rosbridge_server rosbridge_websocket.launch

When I connect using https://pantor.github.io/ros-control-center/ with the url 192.168.137.65:9090 I get the following error from the rosbridge_websocket launchfile:

roslaunch rosbridge_server rosbridge_websocket.launch
... logging to /home/pm/.ros/log/47fc65d8-55fb-11e9-a9a3-00301808c2e2/roslaunch-Jetway32-19301.log
Checking log directory for disk usage. This may take awhile.
Press Ctrl-C to interrupt
Done checking log file disk usage. Usage is <1GB.

started roslaunch server http://Jetway32:38781/

SUMMARY
========

PARAMETERS
 * /rosapi/params_glob: [*]
 * /rosapi/services_glob: [*]
 * /rosapi/topics_glob: [*]
 * /rosbridge_websocket/address: 
 * /rosbridge_websocket/authenticate: False
 * /rosbridge_websocket/bson_only_mode: False
 * /rosbridge_websocket/delay_between_messages: 0
 * /rosbridge_websocket/fragment_timeout: 600
 * /rosbridge_websocket/max_message_size: None
 * /rosbridge_websocket/params_glob: [*]
 * /rosbridge_websocket/port: 9090
 * /rosbridge_websocket/retry_startup_delay: 5
 * /rosbridge_websocket/services_glob: [*]
 * /rosbridge_websocket/topics_glob: [*]
 * /rosbridge_websocket/unregister_timeout: 10
 * /rosbridge_websocket/use_compression: False
 * /rosdistro: kinetic
 * /rosversion: 1.12.14

NODES
  /
    rosapi (rosapi/rosapi_node)
    rosbridge_websocket (rosbridge_server/rosbridge_websocket)

auto-starting new master
process[master]: started with pid [19311]
ROS_MASTER_URI=http://localhost:11311

setting /run_id to 47fc65d8-55fb-11e9-a9a3-00301808c2e2
process[rosout-1]: started with pid [19324]
started core service [/rosout]
process[rosbridge_websocket-2]: started with pid [19338]
process[rosapi-3]: started with pid [19342]
registered capabilities (classes):
 - rosbridge_library.capabilities.call_service.CallService
 - rosbridge_library.capabilities.advertise.Advertise
 - rosbridge_library.capabilities.publish.Publish
 - rosbridge_library.capabilities.subscribe.Subscribe
 - <class 'rosbridge_library.capabilities.defragmentation.Defragment'>
 - rosbridge_library.capabilities.advertise_service.AdvertiseService
 - rosbridge_library.capabilities.service_response.ServiceResponse
 - rosbridge_library.capabilities.unadvertise_service.UnadvertiseService
[INFO] [1554287339.330304]: Rosbridge WebSocket server started on port 9090
[INFO] [1554287373.324739]: Client connected.  1 clients total.
[INFO] [1554287374.701099]: [Client 0] Subscribed to /rosout
[INFO] [1554287374.716470]: [Client 0] Subscribed to /rosout
[ERROR] [1554287374.735829]: Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/rosbridge_server/websocket_handler.py", line 168, in prewrite_message
    yield self.write_message(message, binary)
  File "/usr/lib/python2.7/dist-packages/tornado/gen.py", line 870, in run
    value = future.result()
  File "/usr/lib/python2.7/dist-packages/tornado/concurrent.py", line 215, in result
    raise_exc_info(self._exc_info)
  File "/usr/lib/python2.7/dist-packages/tornado/gen.py", line 956, in handle_yield
    self.future = convert_yielded(yielded)
  File "/usr/lib/python2.7/dist-packages/tornado/gen.py", line 1026, in convert_yielded
    raise BadYieldError("yielded unknown object %r" % (yielded,))
BadYieldError: yielded unknown object None

Any idea what could cause this?