HTTP 409 Conflict — Meaning, Causes & How to Fix
The request conflicts with the current state of the target resource, such as an edit conflict.
- Code
- 409
- Name
- Conflict
- Class
- 4xx Client Error
- Specification
- RFC 9110 §15.5.10
- Cacheable by default
- Only with explicit Cache-Control / Expires
What HTTP 409 means
409 Conflict means the request is valid but cannot be done because of the resource’s current state — for example two users editing the same record, or creating something that already exists. The user can usually resolve the conflict and try again.
Common causes
- Creating a user or record with a value that must be unique.
- Version conflicts in PUT requests or file uploads.
- Git-style merge conflicts in APIs.
How to fix it
For site owners
- Explain the conflict in the body (e.g. which field is taken).
- For optimistic locking,
If-Matchwith412 Precondition Failedis the standard alternative.
For visitors & developers
- Reload the latest version, merge your changes, and resend.
SEO impact
No SEO impact: it is an API/write-request response.
Example 409 response
HTTP/1.1 409 Conflict
Content-Type: application/json
{"error":"email_already_registered"}Related status codes
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Open HTTP Status Codes tool →All status codesFrequently asked questions
What does HTTP 409 mean?
HTTP 409 Conflict is a 4xx Client Error status code. The request conflicts with the current state of the target resource, such as an edit conflict.
Should a duplicate sign-up return 409 or 422?
Both are used. 409 fits “this conflicts with existing data”; 422 fits “this input is invalid”. Pick one and document it.
Which specification defines 409?
It is defined in RFC 9110 §15.5.10.
Is a 409 response cacheable?
Not by default. A 409 response is only stored by caches when it carries explicit freshness information such as Cache-Control: max-age or Expires.