Conflict

What does HTTP 409 Conflict mean?

The request could not be completed due to a conflict with the current state of the target resource, such as an edit conflict or a duplicate that violates a uniqueness constraint.

4xx responses indicate the request was faulty: bad syntax, missing authentication, or a resource that does not exist. The fix usually lives on the client/request side.

Common causes

• Concurrent edits to the same resource (version conflict)
• Creating a resource that already exists (duplicate key)
• Violating a uniqueness or state constraint

How to fix a 409 error

• Fetch the latest version and retry the update
• Use optimistic concurrency (ETags/version fields)
• Handle duplicates gracefully on the client

Related 4xx status codes