[homeassistant.components.mqtt.cover] Payload is not supported (e.g. open, closed, opening, closing, stopped): b'open'

Hi,

i configured a mqtt cover with the follow lines.

mqtt:
  cover:
  - name: "cover"
    unique_id:  Cover123
    command_topic: "fhem/cover/set"
    state_topic: "fhem/cover/state"
    position_topic: "fhem/cover/position"
    payload_close: "close"
    payload_open: "open"
    payload_stop: "stop"
    state_closed: "closed"
    state_closing: "closing"
    state_open: "open"
    state_opening: "opening"
    state_stopped: "stopped"

Send a Command works fine.

But if i receive a state i get the error message:

 [homeassistant.components.mqtt.cover] Payload is not supported (e.g. open, closed, opening, closing, stopped): b'open'

I think the b before the open make the different. It seems for me that the MQTT Server convert something.

has somebody an idea to convert / solve this issue ?

Update: I installed an mosquitto server and I have the same issue …