HTTP 501 Not Implemented — What It Means & How to Fix It

What Does This Error Mean?

A 501 Not Implemented error means the web server received your request but does not have the ability to handle it. The specific type of request your browser made is not something the server is built to do. This is different from a 500 error — the server is not crashing. It is simply saying: 'I do not know how to do what you are asking.' This is almost always a website configuration or development issue — not something you caused.

Affected Models

All web browsers
All websites
Older web server software
APIs and web services

Common Causes

The web server software does not support the type of request that was made
A website feature is partially built but not yet fully implemented on the server
An older server does not support newer web standards your browser uses
A proxy or intermediary server does not understand the request type
The website's server configuration is missing a required module or handler

How to Fix It

Try a different browser. Chrome, Firefox, and Edge each make slightly different types of requests.

Occasionally a browser uses a newer request type that an older server does not yet support.
Clear your browser cache and cookies and try again.

This ensures your browser sends a standard, clean request without any unusual cached instructions.
Disable browser extensions and try reloading.

Extensions can alter how requests are sent, sometimes using methods the server cannot process.
Check if the website has a status page or social media account reporting any known issues.

A 501 during a new feature rollout is sometimes expected while the site is still being updated.
Contact the website's support team with the URL where you saw the error.

This error is a strong indicator of a website bug that developers need to investigate.

When to Call a Professional

As a visitor, there is very little you can do here. This error must be fixed by the website's developers or server administrators. Report the error and the URL to the website's support team. Website owners should check their server software version and ensure all required modules are installed and enabled.

Frequently Asked Questions

What is the difference between a 500 and a 501 error?

A 500 error means the server crashed or encountered an unexpected problem. A 501 error means the server is working fine but does not support what you asked it to do. Both are server-side issues, but a 501 is more specific.

Is this error temporary?

It depends on the cause. If the website is actively being developed, the feature may be added soon. If it is a long-standing configuration issue, it could persist for a long time. Either way, only the website's team can fix it.

Can I do anything to fix this error myself?

Not really — this is a server capability issue. The server lacks the ability to handle your request type. The only thing to try is using a different browser, but the real fix must come from the website.