RECEIVER_NOT_ALLOWED

The receiver of the transaction is not allowed on this path.

HTTP status	403
Group	Relay path
Retryable	No — sending it again changes nothing
Re-sign	NONE — do not ask the user to sign anything

What happened

It is on a deny-list, or the path you used has an allow-list: the free flow and sponsor API keys both restrict which contracts they may call. A sponsor key checks the transaction's receiver field. Single fungible-token payments (ESDTTransfer) to a listed contract are covered. NFT, SFT, Meta-ESDT and multi-token transfers name the sender as receiver, so a sponsor key cannot pay for them yet.

What to do

Relay it on a paid path, or send it to an allowed receiver. For a sponsor key, add the contract to the key's receiver list; an NFT, SFT, Meta-ESDT or multi-token transfer has to be paid by the sender's own plan or a plan that names the sender.

The problem document

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

{
  "type": "https://docs.co-relayer.com/errors/receiver-not-allowed",
  "title": "The receiver of the transaction is not allowed on this path.",
  "status": 403,
  "detail": "A sentence about this specific occurrence.",
  "instance": "req_01JB…",
  "code": "RECEIVER_NOT_ALLOWED",
  "retryable": false,
  "resign": "NONE",
  "hint": "Relay it on a paid path, or send it to an allowed receiver. For a sponsor key, add the contract to the key's receiver list; an NFT, SFT, Meta-ESDT or multi-token transfer has to be paid by the sender's own plan or a plan that names the sender."
}

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