6 Easy Fixes for “Web Server is Returning an Unknown Error”

Key Takeaways
  • Cloudflare error 502 occurs when the web server fails to process a request, often due to server downtime, overload, strict security settings, or incorrect DNS configurations.
  • To fix this error, check server logs, adjust firewall settings, review HAR headers and cookies, disable .htaccess, or temporarily turn off Cloudflare.
  • If troubleshooting fails, contact Cloudflare support for additional assistance and ensure regular server maintenance to prevent future errors.

Encountering a web error such as Cloudflare error code 502 can feel like a sudden barrier of confusion. Where exactly does it come from and why? Well, this vague error message just happens to appear at the most crucial times of our browsing, putting a wall between the next page quite literally.

But no worries, once we get to the bottom of what ‘Web Server is Returning an Unknown Error’ is, you’ll overcome it in no time!

Web Server is Returning an Unknown Error
Web Server is Returning an Unknown Error

What is “Web Server is Returning an Unknown Error”

Cloudflare error 502: Web server is returning to an unknown error’ is a generic message sent by Cloudflare as a result of an unprocessed request. This error is server-side, indicating an issue with the origin web server and not Cloudflare.

Typically, this occurs when the web server is unable to identify a request due to violation of the protocol during the communication process or it simply provides no response.


READ MORE: [FIX] Cloudflare ‘Error 523: Origin is Unreachable’ ➜

Reasons behind Web Server is Returning an Unknown Error

While the causes of error 502 are several, diagnosis of the issue will help in troubleshooting effectively:

  • Server downtime: If the origin web server is experiencing a downtime, either due to maintenance or unexpected breakdown, it can cause the error 502.
  • Server overload: The inability to respond to Cloudflare’s request can be a result of excessive traffic on the server.
  • Strict security settings: Security plugins or Firewall settings may block certain IP addresses that are not whitelisted to protect your server from malicious traffic, including Clouflare’s IP address.
  • Incorrect DNS settings: Since DNS translates domain names into IP addresses, any error in the DNS configuration can lead to Cloudflare incorrectly routing traffic to the server, resulting in an error 502.

READ MORE: How to Fix IPv4/IPv6 ‘No Internet Access’ Error ➜

How to Fix Web Server is Returning an Unknown Error

The ‘Cloudflare error 502: Web server is returning to an unknown error again’ practically offers zero insight into resolving the issue. Therefore, you must try out a few methods to identify where the issue truly lies and troubleshoot accordingly.

1. Check Server Logs

You can start investigating the error by examining the server logs. They record your site’s activity with detailed information about every request made to the server.

Cloudflare's server logs
Cloudflare’s server logs

Checking the server log yourself can help identify overloads or crashes. If the server is experiencing downtime, especially around the time the error started occurring, this may provide clues about blocked requests or other issues.

2. Check FireWall Settings

Checking your Firewall configuration is crucial to ensure that your Cloudflare’s IP addresses are not blocked by overly strict settings. If any such instances are found, whitelist them immediately to allow traffic from these IPs.

READ MORE: How to Disable Windows Firewall ➜

3. Check HAR Header and Cookies

For smooth and secure handling of web traffic, Cloudflare imposes limits on the size of request headers. The overall limit is set to 32 KB, with an individual header size limit of 16 KB. If your website’s request headers exceed these limits, you may encounter a 520-error response, indicating communication issues with the origin server.

Using HAR (HTTP Archive) files can capture detailed information about web browser requests, aiding in reviewing such issues. You can generate them via Google Chrome or any other browser of your choice.

  1. On the webpage displaying error 520, right click and choose Inspect.
inspect option
select inspect from the page giving Cloudflare error
  1. Go to the Network tab.
  2. If the round button is grayed out, click on it. Also check the box for Preserve log.
preserve log in network tab
click on preserve log in network tab
  1. Refresh the page and reopen the Network tab.
  2. Right click anywhere on the Inspector window and click on Save all as HAR with Content.
Inspector window options
click on Save all as HAR with Content
  1. You can then rely on online tools such as Google’s HAR Analyzer to review the HAR file. If the cookies are too large or their usage is excessive, consider using a cookie-free domain.
HAR files contain sensitive data such as passwords, cookies, etc. If you need to share with others, use a text editor to remove such details beforehand.

READ MORE: How To Clear Cookies on iPhone ➜

4. Deactivate .htaccess

For some, disabling the .htaccess file can resolve the issue, as it often triggers the 502 error to begin with. The .htaccess (hypertext access) file is a configuration resource unique to Apache-hosted sites. Disabling it can help determine if it has become corrupted or is causing improper redirects.

  1. Access your site’s root directory to locate the .htaccess file.
  2. Rename the file to .htaccess_disabled which will automatically disable the file.
disable .htaccess
.htaccess_disabled file

5. Disable Cloudflare

It’s also important to review your Cloudflare settings to ensure they are correctly configured. Verify that your website’s domain is correctly associated with Cloudflare in your DNS settings. If you continue to encounter the Cloudflare error 502, consider temporarily disabling Cloudflare entirely.

This approach not only helps isolate whether the issue lies within Cloudflare’s configuration but also bypasses potential proxy issues, establishing direct access to the origin server. It provides a swift method to troubleshoot the problem without the additional layer of Cloudflare’s caching.

  1. Access your Cloudflare dashboard and go to the DNS tab.
  2. Select a domain and toggle off the Proxy status switch.
DNS tab
turn off Proxy status switch in DNS tab

READ MORE: CloudFlare Error 1020 Access Denied: What is It and How to Fix It? ➜

6. Contact Cloudflare Support

Contacting Cloudflare’s Support teams may seem like nothing more than a straw to a drowning man, but often they prove to be a life ring. They provide valuable insights in resolving the matter at hand.

Web Server is Returning an Unknown Error
Cloudflare Help Center

READ MORE: How to Contact Snapchat Support in 2024 [4 Different Ways] ➜


So, resolve your ‘Cloudflare error 502: Web server is returning to an unknown error’ by identifying which specific server issue is the root cause. With continuous server monitoring and settings checks, you can ensure a seamless and smooth browsing experience in the future.

Web server is returning to an unknown error

Is the ‘Web server is returning to an unknown error’ message temporary?

Yes, Cloudflare error 502 is a temporary error caused by a connection failure between the origin web server and Cloudflare. This issue can be easily resolved with several troubleshooting methods as it is not permanent.

Does ‘Web server is returning to an unknown error’ indicate an issue with Cloudflare?

The 502 error occurs when Cloudflare initiates a connection with the origin web server but the specific request is not completed due to an issue on the server side. So, it does not indicate a problem with Cloudflare, as it is a result of the server’s inability to interpret or accept a request.

How can I prevent such errors on my web server?

Preventing unknown errors on your web server requires regular server maintenance and performance checks. In addition, keep your server software updated and ensure correct Firewalls settings to allow necessary traffic.


Kamil Anwar

Kamil is a certified MCITP, CCNA (W), CCNA (S) and a former British Computer Society Member with over 9 years of experience Configuring, Deploying and Managing Switches, Firewalls and Domain Controllers also an old-school still active on FreeNode.