Http 501 ошибка

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

What to do when the web isn’t cooperating

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You may also get a 501 error when the web server is outdated or unmaintained.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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Код 501 Not Implemented означает, что сервер, к которому обращается пользователь, не предоставляет возможности, необходимые для его обработки. Проще говоря, если сервер не понимает указанный метод запроса.

О чем свидетельствует «код 501»

Этот серверный код означает, что метод не может быть обработан, поскольку не поддерживается сервером. Он не может возникать в ответ лишь на два метода запросов — GET и HEAD, поскольку они необходимы серверам для поддержки.

Что делать пользователю, когда в браузере появляется код ошибки «501»

Пользователь, получивший такой код, может написать в службу поддержки сайта о его возникновении. Однако проблема также может быть на стороне пользователя, если его браузер заражен вредоносным программным обеспечением. Проверьте вашу систему антивирусными программами.

Причины возникновения кода «501»

Наиболее распространенные причины возникновения кода 501 таковы:

• вирусы или другое вредоносное программное обеспечение, которые контролируют ваш интернет-браузер;
• сервер, обрабатывающий запросы, перегружен запросами;
• ошибка сервера, обрабатывающего запросы;
• наименее вероятная причина — устаревшее программное обеспечение сервера.

Если вы владелец ресурса, который регулярно возвращает пользователям ошибку 501, обратитесь в службу поддержки вашего хостинг-провайдера.

Вас также может заинтересовать

HTTP response status code 501 Not Implemented is a server error message that is returned to indicate that it does not support a specific feature that is required to complete the HTTP request.

The HTTP response is cacheable by default. If the default behavior needs to be overridden then the HTTP response must include the appropriate HTTP caching headers.

Usage

When the 501 Not Implemented status code is received, it means that the server is not able to fulfill the request due to a server-side deficiency. This is similar to the 405 Method Not Allowed status code, although that is specific in that the client has requested functionality that is not supported. While that may be strictly true at the time of the HTTP request, the functionality may be under development or otherwise not working temporarily. A 405 Method Not Allowed status code suggests that the HTTP request cannot be filled and that the functionality will not be available in the foreseeable future, whereas a 501 Not Implemented status code is used to suggest that it’s “not yet implemented but will be», or “this is something that you can do, once I am ready for you to do it». In this situation, the server can optionally supply a Retry-After HTTP header, suggesting a time for the client to try again.

According to RFC 7231, this is appropriate in cases where the server does not recognize the HTTP request method and thus, cannot fulfill it.

Example

In the example, the client requests a resource and the server responds with a 501 Not Implemented status code because it recognized the HTTP request, but it is not (yet) supported.

Request

POST /requests?id=111&flag=start HTTP/1.1
Host: www.example.re

Response

HTTP/1.1 501 Not Implemented
Content-Type: text/html; charset=UTF-8
Content-Length: 202

<html>
  <head>
    <title>Function Not Implemented<\title>
  </head>
  <body>
    <p>Your request can not be completed because this functionality is currently under development.</p>
  </body>
</html>

Code references

.NET

HttpStatusCode.NotImplemented

Rust

http::StatusCode::NOT_IMPLEMENTED

Rails

:not_implemented

Go

http.StatusNotImplemented

Symfony

Response::HTTP_NOT_IMPLEMENTED

Python3.5+

http.HTTPStatus.NOT_IMPLEMENTED

Java

java.net.HttpURLConnection.HTTP_NOT_IMPLEMENTED

Apache HttpComponents Core

org.apache.hc.core5.http.HttpStatus.SC_NOT_IMPLEMENTED

Angular

@angular/common/http/HttpStatusCode.NotImplemented

Takeaway

The 501 Not Implemented status code is a server error used to indicate that the HTTP request cannot be completed because the server does not support the required functionality at this time.

See also

• 405 Method Not Allowed
• RFC 7231

When something breaks on your site you’ll typically encounter what is called an HTTP status code.

These are delivered to your browser in the HTTP header and to help you troubleshoot what might be wrong. Some status codes you’re probably familiar with include 404 “not found” errors or a 301 redirect for SEO purposes.

Today we’re going to discuss a less common status code, and that is the 501 not implemented error. Follow the steps and recommendations below to resolve it.

What is the HTTP 501 Not Implemented Error?

The Internet Engineering Task Force (IETF) defines the 501 Not Implemented as:

The 501 (Not Implemented) status code indicates that the server does not support the functionality required to fulfill the request. This is the appropriate response when the server does not recognize the request method and is not capable of supporting it for any resource.

A 501 response is cacheable by default; i.e., unless otherwise indicated by the method definition or explicit cache controls.

The 501 not implemented error indicates that the server does not support the functionality required to fulfill the request. This is the appropriate response when the server does not recognize the request method and is not capable of supporting it for any resource (RFC7231, section 6.6.2). A 501 response is also cacheable by default.

Due to the various browsers, web servers, and operating systems, a 501 not implemented error can present itself in a number of different ways. But they all have the same meaning. Below are just a couple of the many different variations you might see on the web:

• “501 Not Implemented”
• “Error 501”
• “HTTP 501”
• “HTTP Error 501 Not implemented”
• “The server either does not recognize the request method, or it lacks the ability to fulfill the request.”

Check Out Our Video Guide to The 501 Error

501 Errors Impact on SEO

Unlike 503 errors, which are used for maintenance mode and tell Google to check back at a later time, a 501 error can have a negative impact on SEO if not fixed right away. If your site is only down for say 10 minutes and it’s being crawled consistently a lot of times the crawler will simply get the page delivered from cache. Or Google might not even have a chance to re-crawl it before it’s back up. In this scenario, you’re completely fine.

However, if the site is down for an extended period of time, say 6+ hours, then Google might see the 501 error as a site level issue that needs to be addressed. This could impact your rankings. If you’re worried about repeat 501 errors you should figure out why they are happening to begin with. Some of the solutions below can help.

How to fix the HTTP 501 Not Implemented Error

A 501 not implemented error is almost always a problem with your web server. There are a few things you can do on your side to try and resolve it, but typically this is the type of error where you’ll need to reach out to your host to fix.

1. Try Reloading the Page

One of the easiest and first things you should try when encountering a 501 not implemented error is to simply wait a minute or so and reload the page (F5 or Ctrl + F5). It could be that the host or server will resolve the issue While you’re waiting, you could also quickly try a different browser to rule that out as an issue.

Another thing you can do is to paste the website into downforeveryoneorjustme.com. This website will tell you if the site is down or if it’s a problem on your side.

2. Clear Your Browser Cache

Whenever you encounter issues like these it can be good to clear your browser cache. Below are instructions on how to clear cache in the various browsers:

• How to Force Refresh a Single Page for All Browsers
• How to Clear Browser Cache for Google Chrome
• How to Clear Browser Cache for Mozilla Firefox
• How to Clear Browser Cache for Safari
• How to Clear Browser Cache for Internet Explorer
• How to Clear Browser Cache for Microsoft Edge
• How to Clear Browser Cache for Opera

3. Disable Proxy Settings

This is very rare, but sometimes you might see a 501 error if you are utilizing a proxy service. Or one might have been set without you even knowing it. Follow these tutorials on how to disable or check to ensure no proxy settings are enabled:

• Disable proxy settings on Windows
• Disable proxy settings on Mac

4. Reach Out To Your Host

Unlike some other HTTP status codes where there is a lot of troubleshooting you can do yourself, 501 errors are almost always an issue on the web server. They aren’t usually caused by a bad plugin or caching issue. Therefore, if it doesn’t resolve itself within a few minutes we recommend simply reaching out to your host. You can also check your host’s status page.

Typical causes of this error on the server might include:

• There was a bad update to the server causing it to not properly respond to the browser’s request.
• There is a misconfiguration in NGINX that needs to be fixed by an engineer.
• The server you’re attempting to access may be overwhelmed and therefore isn’t able to properly generate the request.
• It could also be a billing issue. If you didn’t pay your hosting bills, they might default your site to 501 status before removing the account altogether, giving you another chance to resolve the issue.

At Kinsta, a 501 error can also be due to the fact that your staging site has stopped. Under your site’s Info tab you will see the option to “Start staging environment.”

If for some reason you’re still having issues, simply open a support ticket and we’ll get it fixed immediately.

If you are worried about these happening on your site in the future, you can also utilize a tool like updown.io to monitor and notify you immediately if they occur. It periodically sends an HTTP HEAD request to the URL of your choice. You can simply use your homepage. The tool allows you to set check frequencies of:

• 15 seconds
• 30 seconds
• 1 minute
• 2 minutes
• 5 minutes
• 10 minutes

It will send you an email if and when your site goes down. Here is an example below.

This can be especially useful if you’re on a shared host, who tend to overcrowd their servers. This can give you proof of how often your site might actually be doing down (even during the middle of the night). That’s why we always recommend going with an application, database, and managed WordPress host such as Kinsta.

If you want to keep your site in good shape, make sure to read our in-depth guide on WordPress maintenance.

The HTTP 501 status code is an uncommon WordPress error. Also known as the HTTP 501 not implemented error, it is not like a 404 or 301 error that you would more regularly see in the WordPress ecosystem.

The HTTP 501 not implemented error is a server-based indication that the server cannot fulfill the request because it doesn’t support the functionality.

The 501 error might affect your website SEO in the long term – Google sees it as an offline error, as we’ll discuss in this piece. Here, I’ll discuss the 501 Not Implemented error, its causes, and how you can fix it using four methods.

When you see the 501 not implemented error, you can assume something has gone wrong on the back-end of your website. This denies your GET request because the server actually can’t perform it.

Due to the variety of the web browsers, web servers, and operating systems, a 501 not implemented error can present differently for you. But no matter what the variation, they all mean the same thing. Here are some of the ways it might present itself:

• “Error 501”
• “HTTP 501”
• “501 Not Implemented”
• “HTTP Error 501 Not implemented”

The HTTP 501 error often appears when the hosting server gets offline or unavailable, which means the server is legitimately unable to perform the request. It might significantly impact your website ranking when your website server is down.

How HTTP 501 Error Impacts SEO

If your site is down for 10 minutes, you should be fine even if Google crawls it. But if it goes on for hours, it could impact your SEO rankings. The 501 not implemented error is not like the 503 error, which tells Google to check the website back again later. Google might then see the error as a site-level issue, which could lead to a dip in your rankings.

What Causes the WordPress HTTP 501 Not Implemented Error?

Here are the most common causes behind the 501 not implemented error.

Viruses and Malicious Files

Your browser’s inability to establish communication with the web server might be because of viruses or malicious files in your system.

You can remove the malware from your system by performing a complete scan to ensure there are no security issues in the system that could cause a communication failure.

Outdated Server Stack

This is a less probable cause for error, but the server stack could be outdated, perhaps because your provider has failed to update their stack. Contact your provider in that case. You can face this issue with hosting providers that offer cheap or free services.

Overload on a Server

Another reason is an overloaded server. If your site is getting more traffic than you planned and the server cannot handle that traffic, your request might not be fulfilled by the server and return a 501 not implemented error.

If your server cannot handle the traffic, you may end up with a 501 not implemented error. You can scale your server according to your site’s traffic.

Choose a hosting service that provides easy scaling so you can make the changes in your server specification.

How to Fix the HTTP 501 Not Implemented Error

A 501 not implemented error is primarily a problem with your web server. You’ll need to reach out to your hosting provider to fix this error, but before that, try out the first three methods outlined below to resolve it.

1. Try Reloading the Page

The first and the easiest thing you can do is to try reloading the page whenever you encounter the 501 not implemented error. You can use (F5 and Ctrl + F5) to reload the page.

If that doesn’t work, try to load your site on different browsers and in incognito mode.

Also, load the un-cached version of your site; try to disable or deactivate the cache mechanism (if your site has one) and then reload your website.

Check your site at downforeveryoneorjustme.com as well. This website will tell you if the site really is down or if there is a problem at your end.

2. Clear Your Browser Cache

When you try to reload your website on the same browser or make a new request for the same page, the browser will not reload the page from scratch. You’ll see the cached version of your page, which doesn’t display any changes that you have made on your site.

The second method is to clear your browser cache and then recheck your site to avoid the 501 not implemented error.

Each browser has its own settings. In Google Chrome, go to settings > Privacy and security > Clear browsing data. Select the ‘Cookies and other site data’ and ‘Cached images and files’ options and click the Clear data button.

3. Disable Proxy Settings

To fix the 501 not implemented error, you need to disable proxy settings. With Google Chrome, go to the settings, search proxy, and click on Open your computer’s proxy settings.

Computer proxy settings will open and disable the Automatic and Manual proxy setup. Save the settings and try to re-access your site.

If you’re still seeing a 501 Not Implemented error, there’s just one more thing you need to do.

4. Reach Out to Your Host

The 501 not implemented error does not appear because of a culprit plugin or caching issue; it is mainly a web server issue. If it does not resolve itself, I recommend reaching out to your WordPress host to resolve this issue.

You can try these four methods to resolve the 501 not implemented error. If you are a Cloudways user facing this issue, you can avail Cloudways 24/7 support and discuss your case with the experts.

Downtime on your WordPress site got you down? Switch to Cloudways hosting for lightning speeds and rock-solid uptime. Check out our features here.

You can also utilize a tool like updown.io to monitor your site. This sends an HTTP HEAD request to your site URL and notifies you through email if your site goes down.

Updown.io tool will give you an overall picture of how often your site goes down. A 501 not implemented error mainly occurs in a shared hosting environment, which tends to overcrowd its servers.

I recommend choosing a managed hosting environment like Cloudways that ensures your sites get the performance boost they deserve. Cloudways offers fast speeds, constant availability, and managed security at affordable rates. Check out the Cloudways blog on how you can choose the fastest WordPress Hosting.

Summary

In this article, you learned about the 501 not implemented error, its causes, and how you can fix it with the four specified methods. The 501 is a server-side error, so, understandably, you must choose a WordPress hosting provider that gives you a better environment to avoid downtime that affects your ranking and credibility.

Check out more fixes to WordPress errors here:

• 503 Service Unavailable Error
• 404 Page Not Found Error
• 502 Bad Gateway Error
• 500 Internal Server Error
• 403 Forbidden Error
• White Screen of Death Error

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