409
Conflict
The request conflicts with the current state of the target resource. The server cannot complete the request because it would create an inconsistency — such as a duplicate record or a version mismatch.
What does HTTP 409 mean?
The request conflicts with the current state of the target resource. The server cannot complete the request because it would create an inconsistency — such as a duplicate record or a version mismatch.
Common causes
- 1
Attempting to create a resource that already exists, e.g., registering a username or email that is already taken.
- 2
Optimistic concurrency conflict — two users edited the same record simultaneously and the second save conflicts with the first.
- 3
A state transition that is not allowed, e.g., trying to publish a document that is already published or cancelling an order that has already shipped.
How to fix it
- 1
Read the response body for details about the conflict. Most APIs explain which field or constraint was violated.
- 2
For concurrency conflicts, fetch the latest version of the resource, merge changes, and retry the request.
- 3
For duplicate-key conflicts, check if the resource already exists before creating it, or use an upsert operation if your API supports it.
Monitor for HTTP 409 errors
A sudden spike in 409 errors may indicate a race condition or broken deduplication logic in your application. Uptrack alerts you to status code changes so you can investigate before data integrity issues escalate.
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