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Navigating 505 HTTP Version Not Supported Errors

Vishalini Paliwal
~ 6 min read | Published on Mar 28, 2024


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What is a 505 Error?

When browsing the web, encountering error messages like the infamous "505 HTTP Version Not Supported" can be frustrating. But what exactly does this error mean? Essentially, a 505 error occurs when the server does not support the HTTP protocol version used in the request. It's a server-side error indicating that the server is unable to process the request due to an unsupported protocol version.

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What Are the Possible Causes for 505 Error?

Understanding the root causes of the 505 error can help developers troubleshoot and resolve issues more effectively. Here are some potential reasons behind this error:

  1. Server Configuration: The server may not be configured to support the HTTP protocol version specified in the client's request.
  2. Outdated Client Software: The client's browser or application may be using an outdated or unsupported HTTP protocol version.
  3. Proxy or Gateway Issues: If there's a proxy or gateway between the client and the server, it might not support the requested HTTP version.
  4. Misconfigured Network Devices: In some cases, misconfigured network devices such as load balancers or firewalls can interfere with the HTTP communication, leading to a 505 error.
  5. Protocol Mismatch: The client and server might negotiate to use an unsupported or incompatible HTTP protocol version, resulting in the error.

How to Handle 505 in JavaScript

When encountering a 505 error in JavaScript, it's crucial to handle it gracefully to provide a better user experience. Here's how you can handle it:

  .then(response => {
    if (!response.ok) {
      if (response.status === 505) {
        // Handle 505 error
        console.error("505 HTTP Version Not Supported");
      } else {
        // Handle other errors
        console.error("An error occurred:", response.status);
    } else {
      // Handle successful response
      return response.json();
  .catch(error => {
    console.error("Fetch error:", error);

In this example, we use the Fetch API to make a request to a URL. We check if the response status is 505 and handle it accordingly.

Best Practices for Using 505 Status Code

While encountering a 505 error can be frustrating, following best practices can help mitigate issues and improve the overall reliability of your web applications:

  1. Stay Updated: Ensure that both server and client software are up-to-date with the latest HTTP protocol versions to avoid compatibility issues.
  2. Proper Configuration: Configure servers to support a wide range of HTTP protocol versions to accommodate various client requests.
  3. Error Handling: Implement robust error-handling mechanisms in client-side code to gracefully handle 505 errors and provide informative feedback to users.
  4. Logging and Monitoring: Use logging and monitoring tools to track 505 errors and identify potential issues promptly.
  5. Regular Testing: Regularly test your web applications using different browsers and client software to catch compatibility issues early on.

How to Test 505 Status Code on Postman

Postman provides a convenient way to test HTTP status codes, including the 505 error. Here's how you can do it:

  1. Open Postman and create a new request.
  2. Enter the URL of the server you want to test.
  3. Choose the appropriate HTTP method (e.g., GET, POST).
  4. Send the request.
  5. Check the response status code. If it's 505, you've successfully triggered the error.

How to Test 505 Status Code in DevTools Browser in Chrome

Testing for a 505 error in Chrome's DevTools is straightforward. Follow these steps:

  1. Open Chrome DevTools by pressing F12 or right-clicking on the page and selecting "Inspect."
  2. Navigate to the "Network" tab.
  3. Reload the page or trigger the request you want to test.
  4. Look for the request in the list of network activity.
  5. Click on the request to view detailed information, including the response status code. If it's 505, the error is present.

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Frequently Asked Questions

Q: What should I do if I encounter a 505 error?

A: First, check if your client software (browser or application) is up-to-date. If it is, contact the website administrator to report the issue.

Q: Can I fix a 505 error on my own?

A: In most cases, 505 errors require action on the server-side. However, ensuring your client software is updated can sometimes resolve the issue.

Q: Is a 505 error the same as a 404 error?

A: No, a 404 error indicates that the requested resource could not be found on the server, while a 505 error specifically relates to unsupported HTTP protocol versions.

Q: How can I prevent 505 errors in my web applications?

A: Stay informed about the latest HTTP protocol versions and ensure compatibility between client and server software. Regularly test your applications for compatibility issues.

Q: Are 505 errors common?

A: While not as common as some other HTTP errors like 404 or 500, 505 errors can still occur, especially in environments with a mix of outdated and updated client-server software.


Encountering a 505 HTTP Version Not Supported error can be frustrating for both users and developers. However, by understanding its causes and following best practices, developers can effectively handle and mitigate these errors, ensuring a smoother user experience. Remember, staying updated and testing regularly are key to maintaining the reliability of your web applications.

Additionally, tools like Zipy can help monitor and handle errors with session replay capabilities, providing valuable insights into user interactions. Check out Zipy's error handling solution here for more information.

Read more resources on 5xx error status codes

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