409 Conflict (HTTP Status Code 409)

HTTP status code 409 indicates that the server encountered a conflict while processing the request, typically because the request is inconsistent with the current state of the server.

Causes of 409 Status Code

Concurrent Modifications: Conflicts may arise when two or more users or processes attempt to modify the same resource simultaneously.
Resource Version Conflict: In APIs that involve resource versions, if the client tries to update an outdated resource version, the server may return a 409 status code.
Validation Failures: The data in the client’s request does not meet the server’s validation rules.
State Dependency: The request depends on a specific resource state, which does not match the current state expected by the request.
Resource Locking: The resource may be locked by another process, preventing the completion of the requested operation.

When the server returns a 409 status code, it typically includes an error message in the response body that explains the reason for the conflict. This message can provide guidance on how to resolve the conflict.

HTTP/1.1 409 Conflict
Content-Type: text/html
Content-Length: 223

<html>
<head><title>409 Conflict</title></head>
<body>
<h1>Conflict</h1>
<p>The request could not be completed because it conflicts with the current state of the resource. Please try again.</p>
<hr>
<address>Apache/2.4.1 (Unix) Server at www.example.com Port 80</address>
</body>
</html>

In this example, the status code 409 indicates that the server cannot process the request due to a conflict with the current state of the resource. The response body contains a simple HTML page informing the user that the request cannot be completed.

Steps for the Client When Receiving a 409 Error

Check Request Data: Ensure that the data being sent matches the server’s expectations.
Avoid Concurrent Modifications: If possible, prevent multiple users or processes from modifying the same resource simultaneously.
Use Optimistic Locking: Include version information in the request so the server can verify the resource’s latest state.
Review Error Message: Carefully read the error message returned by the server to understand the specific reason for the conflict.
Contact Website Administrator: If the conflict cannot be resolved, reach out to the website administrator or service provider for assistance.
Retry Request: If the conflict is temporary, wait a moment and then retry the request.

The 409 error typically requires intervention from either the client or server to resolve. Understanding the cause of the conflict and taking appropriate measures is key to addressing such issues.

409 Conflict (HTTP Status Code 409)

Causes of 409 Status Code

Steps for the Client When Receiving a 409 Error

Related 4xx error code