501 HTTP Status Code Error: What It Is and How to Fix It

What to do when the web isn't cooperating

By
Nicholas Congleton
Nick Congleton
Nicholas Congleton
Writer
  • William Patterson University
Nick Congleton has been a tech writer and blogger since 2015. His work has appeared in PCMech, Make Tech Easier, Infosec Institute, and others.
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Updated on February 23, 2021

What to Know

  • A 501 HTTP isn’t a problem with your computer or web browser. It’s a problem with the web server or the site running on it.
  •  Most errors occur when the owner of a web server hasn't enabled a feature needed to complete a server request.
  • Troubleshooting tips: Update server, reboot or restart web service, update web application, look for missing modules, check server logs.

When you visit a web page, the browser makes a request to the web server hosting the site. When the server cannot fulfill the request, you receive an HTTP 501 error.

What Causes the HTTP 501 Error?

There are a few common reasons why a server can’t meet your browser’s request, causing the HTTP 501 error. Most commonly, the owner of the web server hasn’t enabled a feature needed to complete the request. There’s also the chance that they haven’t installed a required piece of software or plugin for the web server.

You may also get a 501 error when the web server is outdated or unmaintained. In rarer cases, the site owner set something up wrong, and the web server software they chose isn’t compatible with a feature on the site.

How to Solve the HTTP 501 Error

Before you start, there is no real way to solve the 501 error as a visitor to a website. The problem isn’t with your computer or web browser. It’s a problem with the web server or the site running on it. The most you can do is reach out to the owner of the site and let them know something’s wrong.

If you are the site owner, these steps can help you get to the bottom of the problem causing the HTTP 501 error.

  1. Try updating the server. On Debian and Ubuntu servers, run: 

    $ sudo apt update && sudo apt upgrade

    For CentOS and RHEL run: 

    $ sudo dnf update  

  2. Next, either reboot your server or restart the web server service. Apache users should run: 

    $ sudo systemctl restart apache2

    On some systems, that’s a little different. 

    $ sudo systemctl restart httpd

    Restarting Nginx is similar. 

    $ sudo systemctl restart nginx

  3. If you’re still seeing the error, try updating your web application. Web platforms like WordPress receive frequent updates that you can run through your dashboard. If the dashboard is accessible through the web interface without getting the 501 error, try running an update.

  4. Look for any missing modules for your web server. There are tons of Apache modules for compatibility with a variety of programming languages, like PHP, Python, and Ruby. Make sure that you have the ones that you need installed.

  5. Finally, check the server logs. Both Apache and Nginx keep their logs in /var/log Check to see if you can determine the cause of the 501 from what the server itself is logging.  

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