What causes HTTP 409 Conflict?

Attempting to create a resource that already exists. Concurrent edit conflict (optimistic locking). Version mismatch during update. Duplicate entry violation.

HTTP 409 Conflict

Client Error

The request conflicts with the current state of the resource on the server. Common in concurrent editing scenarios.

Common Causes

Attempting to create a resource that already exists
Concurrent edit conflict (optimistic locking)
Version mismatch during update
Duplicate entry violation

How to Fix

Fetch the latest version and retry
Use conditional requests (If-Match) for updates
Handle duplicate entry errors in application logic

Related Status Codes

412 Precondition Failed 422 Unprocessable Entity 200 OK

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View the Full HTTP Status Code Reference