HTTP 409 Conflict

Resource conflicts and concurrent update problems

What the 409 Status Code Means

The HTTP 409 Conflict status code indicates that the request could not be completed because it conflicts with the current state of the target resource.

This error commonly occurs when a client attempts to update or modify a resource while another change has already altered its state.

Common Causes of HTTP 409 Errors

Example of a 409 Response

HTTP/1.1 409 Conflict
Content-Type: application/json

APIs often return a structured error response describing the specific conflict so that the client can resolve the issue.

Common Scenarios

Many modern APIs use version identifiers or ETags to detect and prevent these types of conflicts.

How Developers Diagnose 409 Errors

Related HTTP Status Codes

Summary

The HTTP 409 Conflict status code indicates that a request cannot be processed due to a conflict with the current state of the target resource. These errors often occur when multiple clients attempt to modify the same resource simultaneously.

Proper version control and conflict detection mechanisms help prevent data inconsistencies in modern web applications and APIs.