unsupported_message

Not supported by this server

The server does not serve this request — a newer client against an older deployment, or a codec the receiver did not claim it can decode.

What to do: Nothing: the SDK remembers the refusal and stops asking.

Where it comes from:

• Signaling — a client's connect, a request, or an event

Branch on code; detail is for your logs and never for a user. All error codes.