HTTP 521
Web Server Is Down (Cloudflare)
Cloudflare
What does "HTTP 521 Web Server Is Down (Cloudflare)" mean?
Plain-English Meaning
Cloudflare-specific. Cloudflare can't connect to the origin server at all.
Common Causes
- Origin server down
- Origin server blocking Cloudflare IPs
- Origin server not listening on expected port
What Users Can Do
The site is effectively down. Wait for the owner to fix it.
What Developers Can Do
Check that your origin server is running and accepting connections. Verify Cloudflare IPs are whitelisted in your firewall.
Related Status Codes
520
Web Server Returned Unknown Error (Cloudflare) 522
Connection Timed Out (Cloudflare) 523
Origin Is Unreachable (Cloudflare) 524
A Timeout Occurred (Cloudflare)
Web Server Returned Unknown Error (Cloudflare) 522
Connection Timed Out (Cloudflare) 523
Origin Is Unreachable (Cloudflare) 524
A Timeout Occurred (Cloudflare)
Seeing HTTP 521 on a specific site?
Check if the site is experiencing this error for everyone or just you.
Check Website Status