conflict

HTTP 409 — Conflict

When you see it

An Idempotency-Key was reused with a different body, or a request with that key is still in flight.

What to do

Use a fresh key for a genuinely new request, and the SAME key with the SAME body when retrying.

The response

Every error is RFC 9457 problem+json:

{
  "type": "https://devs.inittasks.com/errors/conflict",
  "title": "Conflict",
  "status": 409,
  "detail": "a sentence for a developer; never branch on it",
  "instance": "/todos/8E4F2A1B",
  "request_id": "3f9a1c7e-2b44-4d1e-9c30-5a7e8b2d1f60"
}

Branch on type, never on detail or on the HTTP status alone — several codes share a status.