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

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Updated November 20, 2019

What Is the HTTP 501 Error?

When you visit a web page, your browser makes a request to the web server hosting the site. Usually, everything is works just fine and the page loads up. When the server can’t fulfill the request, you’ll receive an HTTP 501 error.

What Causes the HTTP 501 Error?

The words Error 501 overlaid on computer code. — Borka Kiss / iStock / Getty Images

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. Then, there’s the chance that they haven’t installed a required piece of software or plugin for the web server. You also might get a 501 error when the web serer is outdated or unmaintained. In some rarer cases, the site owner set something up wrong, and the web server software they chose isn’t compatible with a feature on their 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.

Try updating the server. On Debian and Ubuntu servers, run:
```
$ sudo apt update && sudo apt upgrade
```
For CentOS and RHEL run:
```
$ sudo dnf update  
```
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
```
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.
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.
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.