409 Conflict
The request fights the current state — a duplicate slug, a stale version.
409Client error
- What it means
- The request fights the current state — a duplicate slug, a stale version.
- In practice
- 409 says the request was well-formed but cannot be applied to the world as it is now: the username is taken, the record changed since you read it, the state machine will not allow that transition. Retrying unchanged will not help; re-read the current state, reconcile, and try again. APIs doing optimistic locking often use 409 (or 412) when your version is stale.
- Whose problem is it?
- The request. Retrying it unchanged will get the same answer.
Often confused with