HTTP 409 Conflict vs 510 Not Extended
HTTP 409 (Conflict) is a 4xx Client Error response, while 510 (Not Extended) is a 5xx Server Error response. 409 indicates that the request conflicts with the current state of the server. Often due to concurrent modification or business rule violations. In contrast, 510 means that further extensions to the request are required for the server to fulfill it.
Description
The request conflicts with the current state of the server. Often due to concurrent modification or business rule violations.
When You See It
When trying to create a resource that already exists, or updating a resource that was modified by another request.
How to Fix
Refresh the resource state, resolve conflicts, and retry. Use ETags for optimistic concurrency.
Description
Further extensions to the request are required for the server to fulfill it.
When You See It
When an HTTP extension required by the server is not present in the request.
How to Fix
Add the required extension headers to your request.
Key Differences
409 is a 4xx Client Error response, while 510 is a 5xx Server Error response.
HTTP 409: The request conflicts with the current state of the server. Often due to concurrent modification or business rule violations.
HTTP 510: Further extensions to the request are required for the server to fulfill it.
You encounter 409 when when trying to create a resource that already exists, or updating a resource that was modified by another request.
You encounter 510 when when an HTTP extension required by the server is not present in the request.
When to Use Which
For 409 (Conflict): Refresh the resource state, resolve conflicts, and retry. Use ETags for optimistic concurrency. For 510 (Not Extended): Add the required extension headers to your request.