HTTP status code 520 (Web Server Returned an Unknown Error) means: The website's server returned an empty, unknown or unexpected response to Cloudflare. Yes, a server error: the website failed to handle the request. Usually only the site owner or host can fix it.
Is it an error?
Yes, a server error: the website failed to handle the request. Usually only the site owner or host can fix it.
Common causes
- Error in the website's code, a plugin or a recent update
- Firewall or security plugin blocking the proxy/CDN's IP addresses
- Cookies or headers too large
- Server misconfiguration (.htaccess, server or proxy rules)
If you are visiting the site
- Reload the page
- Wait a few minutes before trying again
- Contact the website if the problem continues
If you run the website
- Check the server error logs at the time of the error
- Allow Cloudflare's IP ranges in the server firewall and security plugins
- Reduce cookie size or raise header size limits
- Ask your hosting provider to check the server
Frequently asked questions
What does HTTP 520 mean?
HTTP status code 520 (Web Server Returned an Unknown Error) means: The website's server returned an empty, unknown or unexpected response to Cloudflare.
Is HTTP 520 an error?
Yes, a server error: the website failed to handle the request. Usually only the site owner or host can fix it.
How do I fix a 520 error?
If you are visiting the site: Reload the page; Wait a few minutes before trying again; Contact the website if the problem continues. If you run the website: Check the server error logs at the time of the error; Allow Cloudflare's IP ranges in the server firewall and security plugins; Reduce cookie size or raise header size limits; Ask your hosting provider to check the server.