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HTTP Status Code
409 Conflict
Client ErrorThe request could not be completed because it conflicts with the current state of the resource.
HTTP status code reference, response example, common causes, fixes, and related status codes.
What does HTTP 409 Conflict mean?
HTTP 409 Conflict is a status code sent by a server to indicate the result of an HTTP request.
Status codes help browsers, APIs, apps, and backend systems understand whether a request succeeded, failed, was redirected, or needs additional action.
In practice, HTTP 409 Conflict usually appears when a server responds under specific request, validation, permission, or infrastructure conditions.
Response example
HTTP/1.1 409 Conflict
HTTP example
HTTP/1.1 409 Conflict
Common causes
- Version mismatch
- Duplicate resource creation attempt
- Concurrent update conflict
How to fix it
- Reload the latest resource state
- Retry with updated data
- Resolve duplicate or versioning issues
Common mistakes
- Assuming the status code alone explains the full backend issue
- Ignoring related response headers that add important context
- Treating temporary errors as permanent failures
- Retrying too aggressively without checking the cause
- Debugging the frontend only when the problem is server-side
How browsers and APIs use it
Browsers, APIs, and backend services use HTTP status codes to understand the outcome of a request. Depending on the status code, an application may render content, retry a request, redirect the user, show an error, or trigger a different flow in the client or server.
Developer note
HTTP 409 is common in APIs with versioning, optimistic locking, or uniqueness constraints.