API errors

idempotency_key_reused

This `X-Idempotency-Key` was already used with a different request body.

422application/problem+json

What it means

An idempotency key pins one request for 48 hours: a replay with the same key must carry an equivalent body to receive the original response. This key arrived with a different body, so the API refused rather than guess which request you meant.

422 · application/problem+json

{
  "type": "https://developers.firsty.app/errors/idempotency_key_reused",
  "title": "Unprocessable entity",
  "status": 422,
  "detail": "This idempotency key was already used with a different request body.",
  "code": "idempotency_key_reused"
}

How to handle it

Generate a fresh key (a UUID, up to 255 characters) for every logical operation, and reuse a key only to replay the identical request.
If you intended a replay, compare the body with the original. Key order does not matter; values do.

Errors reference