HTTP 501 Response Status Code Guide: What is it, Usage, Methods

Jun 10 2024 by Oskay Günaçar

What Is HTTP 501 Status Code?

The HTTP 501 Not Implemented status code indicates that the server does not support the functionality required to fulfill the request. This response is sent when the server either does not recognize the request method or lacks the ability to fulfill the request. It is primarily intended for use when the server does not support a certain feature that is necessary for the request to be processed.

Importance of the HTTP 501 Status Code in SEO

The HTTP 501 Not Implemented status code is relatively rare and generally indicates that the server does not support the functionality required to fulfill the request. While it may not directly impact SEO as much as more common status codes like 200, 404, or 301, it still holds some importance for the following reasons:

  1. User Experience:

    • If users encounter a 501 status code, it means that the server is not able to process their request, which can lead to a poor user experience. A poor user experience can indirectly affect SEO, as search engines prioritize websites that provide good user experiences.
  2. Crawlability:

    • Search engine crawlers, like Googlebot, may encounter a 501 status code when trying to access certain pages. If these pages cannot be crawled due to unsupported methods, the content on those pages will not be indexed, potentially leading to reduced visibility in search results.
  3. Server Health and Maintenance:

    • Frequent occurrences of 501 status codes can indicate issues with the server configuration or the web application itself. Regularly monitoring and addressing these issues can help ensure that your website remains fully functional and accessible, maintaining a healthy environment for both users and search engines.
  4. Technical SEO:

    • Technical SEO involves ensuring that a website is properly configured to be crawled and indexed by search engines. Encountering 501 errors may suggest that certain methods or functionalities need to be implemented or fixed to ensure complete accessibility and indexability.
  5. Log Analysis:

    • Analyzing server logs can reveal instances of 501 status codes. Understanding when and why these errors occur can help in diagnosing issues with the server or application and taking corrective actions. Keeping logs clean from such errors can contribute to better overall site performance and SEO health.

To mitigate the impact of HTTP 501 status codes on SEO:

  • Ensure your server supports the necessary request methods for your website's functionality.
  • Regularly check server logs for any instances of 501 errors and address them promptly.
  • Implement proper error handling and user-friendly error pages to guide users and search engine bots when they encounter such issues.

By addressing and preventing 501 errors, you can maintain a better user experience, improve crawlability, and ensure the technical health of your website, all of which are beneficial for SEO.

How to Fix the HTTP 501 Error From the Website?

Fixing an HTTP 501 Not Implemented status code typically involves ensuring that the server is configured to support the functionality required by the client's request. Here are some steps to diagnose and fix this issue:

  1. Verify the Request Method:

    • Ensure that the request method (e.g., GET, POST, PUT, DELETE) being used is supported by the server. Some servers might not support certain methods or might need configuration to do so.
  2. Check Server Configuration:

    • Review the server configuration files (e.g., Apache's httpd.conf or Nginx's nginx.conf) to make sure the server is set up to handle the specific request methods.
    • Ensure that necessary modules or extensions are installed and enabled on the server to support the required methods.
  3. Update Server Software:

    • Make sure the server software is up to date. Sometimes, an outdated server software version might not support certain methods.
    • Update any relevant plugins or frameworks that the server relies on.
  4. Check Application Code:

    • Review the application code to ensure that it handles all the necessary request methods correctly.
    • Ensure that there are no logical errors in the code that might cause unsupported methods to be used.
  5. Server Logs:

    • Examine the server logs to identify specific details about the 501 errors. Server logs can provide insights into why a particular method is not implemented or supported.
    • Look for patterns or specific endpoints that are causing the errors to pinpoint the issue.
  6. Security Settings:

    • Check security settings such as firewalls or security plugins that might be blocking certain request methods.
    • Ensure that any security policies or rules are not inadvertently causing the 501 errors.
  7. Consult Documentation:

    • Refer to the server documentation for information on how to enable support for various request methods.
    • Consult the documentation of any web frameworks or libraries being used to ensure they support the required methods and are correctly configured.
  8. Custom Error Handling:

    • Implement custom error handling to provide a more informative message to the user if a 501 error occurs. This can help in identifying the issue more quickly.
  9. Test Changes:

    • After making configuration changes or code updates, thoroughly test the website to ensure that the 501 errors are resolved.
    • Use tools like cURL or Postman to send requests with different methods to verify that the server now supports them.
  10. Contact Hosting Provider:

    • If you are using a managed hosting service, contact your hosting provider for assistance. They may be able to help you diagnose and resolve the issue.

By following these steps, you can identify the root cause of the HTTP 501 Not Implemented status code and take appropriate actions to fix it, ensuring that your server can handle the required request methods.

How to Check HTTP 501 Status Code?

To check for an HTTP 501 Not Implemented status code, you can use several methods, including web browsers, developer tools, command-line tools, and online services. Here are some effective ways to do it:

1. Using a Web Browser

Most modern web browsers provide developer tools that can help you check HTTP status codes. Here’s how to do it:

Google Chrome or Firefox:

  • Open the browser.
  • Press F12 or Ctrl+Shift+I (Windows/Linux) or Cmd+Opt+I (Mac) to open Developer Tools.
  • Go to the Network tab.
  • Reload the page.
  • Look at the list of network requests. You can see the status codes in the Status column.

2. Using Command-Line Tools


cURL is a powerful command-line tool to transfer data from or to a server. To check the HTTP status code of a URL using cURL, you can use the following command:

curl -I

The -I option fetches the headers only. Look for the HTTP/1.1 501 Not Implemented line in the output.


You can also use wget to check the status code:

wget --server-response --spider 

Look for the HTTP status code in the server response section.

3. Using Online Tools

There are several online tools available that can help you check the HTTP status code of a URL. A popular one include:

Simply enter the URL you want to check, and the tool will display the HTTP status code.

4. Using Programming Languages


You can use Python with the requests library to check the status code:

import requests

response = requests.get('')

If the status code is 501, it will be printed as 501.

5. Using Web Application Monitoring Tools

Tools like Postman can be used to manually send requests and check responses, including status codes. Postman allows you to specify request methods and see detailed responses.


  • Open Postman.
  • Enter the URL.
  • Select the HTTP method (GET, POST, etc.).
  • Click Send.
  • Check the response status code in the response section.

What is the Browser Compatibility of HTTP 501 Status Code?

The HTTP 501 Not Implemented status code is well-supported across all modern browsers. This status code is part of the HTTP/1.1 standard, and all major browsers are designed to handle it appropriately. Here’s a detailed look at browser compatibility for the HTTP 501 status code:

Browser Compatibility Overview

  1. Google Chrome: Fully supports the HTTP 501 status code. Chrome will display a generic error page indicating that the server does not support the functionality required to fulfill the request.

  2. Mozilla Firefox: Fully supports the HTTP 501 status code. Firefox will show a similar error page indicating the method is not implemented by the server.

  3. Microsoft Edge: Fully supports the HTTP 501 status code. Edge handles this status code as expected, displaying an error message to the user.

  4. Safari (macOS and iOS): Fully supports the HTTP 501 status code. Safari will display an error page informing the user that the method is not implemented.

  5. Opera: Fully supports the HTTP 501 status code. Opera will show an error page that explains the server does not support the requested method.

Handling in Different Browsers

Regardless of the browser, when an HTTP 501 status code is encountered, the browser will:

  • Display a standard error message indicating that the request method is not supported by the server.
  • Prevent the requested action from being performed, as the server has explicitly stated it cannot handle the request method.


Understanding and addressing the HTTP 501 Not Implemented status code is crucial for maintaining a healthy and functional website. While it may be less common than other status codes, its occurrence can still impact user experience, crawlability, and overall server health. By ensuring your server supports all necessary request methods, regularly monitoring server logs, and implementing proper error handling, you can prevent and quickly resolve 501 errors. This proactive approach not only enhances the user experience but also contributes to better SEO performance. Stay vigilant and regularly update your server and application configurations to handle all required functionalities seamlessly.

Oskay Günaçar
Oskay Günaçar is a Technical SEO expert and backend developer. His main areas of interest are back-end programming, Python, Django, Go, semantic SEO, technical SEO. With more than 5 years of SEO experience, he has held SEO specialist positions at İkiler, Webtures, Boosmart, and companies, and has been involved in numerous projects as an outsourced expert. Through the TechSEOHub website, he aims to share the expertise and experience he has gained from managing and developing (SEO) processes for many successful and large websites in the industry, and to produce content for easy access to accurate and high-quality information.