RELAYER_UNKNOWN

The relayer address in the transaction is not one of ours.

HTTP status	422
Group	Relay path
Retryable	No — sending it again changes nothing
Re-sign	NONE — do not ask the user to sign anything

What happened

Only addresses from the on-chain relayer registry can be co-signed.

What to do

Call the assign endpoint and use the relayer it returns.

The problem document

Every error is application/problem+json (RFC 9457) with the same shape:

{
  "type": "https://docs.co-relayer.com/errors/relayer-unknown",
  "title": "The `relayer` address in the transaction is not one of ours.",
  "status": 422,
  "detail": "A sentence about this specific occurrence.",
  "instance": "req_01JB…",
  "code": "RELAYER_UNKNOWN",
  "retryable": false,
  "resign": "NONE",
  "hint": "Call the assign endpoint and use the relayer it returns."
}

See the error model for what each member means and how to handle unknown codes.