`gateway_return_unknown`

HTTP 404not_found

No sign-in is waiting for this return, or its time is over.

Handling it

Fix the request and send it again. message says what is wrong, and param names the parameter where there is one. Keep the request_id: it lets Parasend find the request.

The error, as the API returns it

{
  "error": {
    "type": "not_found",
    "code": "gateway_return_unknown",
    "message": "No sign-in is waiting for this return, or its time is over.",
    "param": null,
    "request_id": "req_5e69684dc3de68bf8651a712"
  }
}