Error 520 is reported on the website

General Rules
1

What is the name of the domain?

file.onew.pp.ua

What is the error number?

520

What is the error message?

Web server is returning an unknown error

What is the issue you’re encountering

I have a file.onew.pp.ua domain hosted on cloudflare, but it is inaccessible and the error message says web server is returning an unknown error Error code 520. According to the official documentation, the 5xx error is that the server returned an empty response, but I’m pretty sure that there is nothing wrong with my server. Because my other domain file.onedabuliu.cn the same configuration as file.onew.pp.ua, but it’s accessible. So I now think it’s cloudflare’s Amsterdam that’s having a problem, and several of my subdomains are getting errors from Amsterdam’s servers.

What steps have you taken to resolve the issue?

Register a new domain name and host to Cloudflare and use Cloudflare proxy and origin rules but still can’t access it. Without using Cloudflare’s web proxy, you can access the website smoothly using the domain port.

What are the steps to reproduce the issue?

The registered domain name is hosted on Cloudflare, the proxy is enabled, and the origin rules are enabled.

Screenshot of the error

Snipaste_2025-03-22_22-51-22.png
Snipaste_2025-03-22_22-51-22.png1891×950 49.7 KB

2

Hello,

Error 520 indicates origin server returns an empty, unknown, or unexpected response to Cloudflare.

This error is often triggered by:

  • Origin server crashes or misconfigurations.
  • Firewalls or security plugins blocking Cloudflare IPs at your origin.
  • Headers exceeding 16 KB (often due to excessive cookies).
  • Empty or malformed responses lacking an HTTP status code or response body.
  • Missing response headers or origin web server not returning proper HTTP error responses .
  • Incorrect HTTP/2 configuration at the origin server.

Contact your hosting provider or site administrator and share the necessary error details to assist with troubleshooting. Request a review of your origin web server error logs for crashes and check for common causes mentioned in the previous section.

For further information, kindly review this document : Troubleshooting Cloudflare 5XX errors · Cloudflare Support docs

Thank you !!