Millions of websites sit behind Cloudflare, which receives visitors' requests and passes them on to the website's own server, called the origin. When Cloudflare can't get a proper answer from the origin, it shows a branded error page with a 52x code.
For visitors, all of these mean the same thing: the website's own server has a problem, and Cloudflare itself is working.
What each code means
- 520 Web server returned an unknown error: the origin sent back an empty, invalid or unexpected response.
- 521 Web server is down: the origin refused the connection. The web server is stopped, or it's blocking Cloudflare's IP addresses.
- 522 Connection timed out: Cloudflare couldn't complete a connection to the origin in time. The server is overloaded, offline, or a firewall is dropping traffic.
- 523 Origin is unreachable: Cloudflare couldn't find a route to the origin, often because of a wrong DNS record.
- 524 A timeout occurred: the origin accepted the connection but didn't send a response within 100 seconds.
- 525 SSL handshake failed and 526 Invalid SSL certificate: the HTTPS connection between Cloudflare and the origin failed.
What you can do as a visitor
Wait a few minutes and reload. These errors are on the website's side, so changing your browser or network rarely helps. You can confirm with our website checker. If it's a service you use often, look it up in our status list to see whether others are reporting problems.
If you own the website
- For 521 and 522, check the web server is running and that your firewall allows Cloudflare's IP ranges on ports 80 and 443.
- For 523, check your DNS records in Cloudflare point at the right origin IP.
- For 524, move long-running work to background jobs.
- For 525 and 526, install a valid certificate on the origin (a free Cloudflare Origin Certificate works) and check your SSL/TLS mode.
Questions
Is Cloudflare down when I see a 52x error?
Usually not. These errors mean Cloudflare is working but can't reach the website's own server. A real Cloudflare outage affects many unrelated sites at once.
How long do Cloudflare 522 errors last?
Until the website's server comes back or its firewall is fixed. Short ones last minutes; a server that's fully down can take hours.