HTTP Reference
HTTP 409 Conflict
The request conflicts with the current state of the resource.
Common Causes
- Duplicate unique value (email, username, slug).
- Version mismatch in optimistic concurrency control.
- State transition not allowed in current resource status.
Debugging Notes
- Return conflict details so clients can recover deterministically.
- Use idempotency keys for create endpoints to reduce duplicate conflicts.
Example Response
{
"status": 409,
"error": "Conflict",
"message": "Resource already exists"
}