tool::http-status-detail
409 Conflict
The request conflicts with the current state of the server.
Status Code
409
Name
Conflict
Category
4xxDetailed Explanation
HTTP 409 Conflict indicates the request could not be completed due to a conflict with the current state of the resource. It occurs when two clients try to modify the same resource simultaneously, when duplicate data is submitted, or when a version mismatch prevents an update. It is commonly used in REST APIs to implement optimistic locking.
Common Causes
- ▸Attempting to create an account with a username or email that already exists
- ▸Optimistic locking failure (ETag mismatch / version conflict)
- ▸A concurrent edit caused a data conflict
- ▸Trying to create a child resource without a valid parent resource
How to Fix
- 1.Fetch the conflicting resource first to inspect its current state
- 2.If using ETag-based optimistic locking, update to the latest version and retry
- 3.For duplicate key conflicts, consider updating the existing record instead
- 4.Read the response body to understand the specific cause of the conflict
Related HTTP Headers
Content-TypeETagResponse Example
HTTP/1.1 409 Conflict
Content-Type: application/json
{"error":"conflict","message":"Username 'john_doe' already exists"}Related Status Codes
400Bad RequestThe server could not understand the request due to invalid syntax.→401UnauthorizedAuthentication is required and has failed or not been provided.→402Payment RequiredReserved for future use; some services use it for payment walls.→403ForbiddenThe server refuses to fulfill the request (authenticated but unauthorized).→404Not FoundThe requested resource could not be found.→
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