409 Conflict
The request conflicts with the current state of the resource.
What it means
Duplicate unique value, version conflict, or an invalid state transition such as cancelling a shipped order.
What your client should do
Fetch the current state, resolve the conflict, and try again. Do not blindly retry.
Should you retry?
Only after you change the request.
Try it
The free practice API returns this status on demand, with the headers a well-behaved API would send. Call GET /api/play/status/409 from Endpoint Client and open the Explain tab.
Related codes
412 Precondition Failed
A conditional header did not match.
422 Unprocessable Content
The body is well-formed but semantically invalid.
Defined in RFC 9110. All status codes and headers