What does HTTP 409 mean?
The request conflicts with the current state of the resource.
Common causes and when you see it
Duplicate unique values, edit conflicts or version mismatches.
How to fix or handle it
Fetch the latest state, resolve the conflict and retry.
Test it yourself
Send a request with the online API tester, inspect the response with the HTTP header checker, or host an endpoint that returns 409 with the mock API generator to see how your app reacts.
HTTP 409 questions
The request conflicts with the current state of the resource.
Duplicate unique values, edit conflicts or version mismatches.
Fetch the latest state, resolve the conflict and retry.