501 Not Implemented

What it means

Usually the server does not recognize the request method at all.

Common causes

• An unsupported HTTP method.

How to fix it

1. Use a supported method, or implement the feature on the server.

Example response

HTTP/1.1 501 Not Implemented
Content-Type: text/plain; charset=utf-8

Worked example

A client sends a method or protocol feature that the server does not implement and receives 501. The owner must add support or configure the origin; if the server supports the method but this resource forbids it, 405 is the more specific response.

How to read this response

1. Find the status line in your browser's Network panel, API client, or server access log.
2. Read the response body and headers shown above; headers such as Location, Allow, Retry-After, and WWW-Authenticate explain the next step.
3. Use the code's class to orient your diagnosis: informational, successful, redirected, request-related, or server-side.

How to check a status code

Enter a URL in the HTTP Status Checker to see its status code, every redirect hop, and response time. For redirect-heavy pages, the Website Speed Test shows how much time redirects add.

Frequently asked questions

What it means: HTTP 501

501 Not Implemented: The server does not support the functionality needed to fulfil the request.

Common causes: 501

An unsupported HTTP method.

How to fix it: HTTP 501

Use a supported method, or implement the feature on the server.

Tools