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Original file line number Diff line number Diff line change
@@ -1,4 +1,4 @@
---
production---
pcx_content_type: troubleshooting
title: Error 521
source: null
Expand All @@ -24,4 +24,4 @@ Contact your hosting provider or site administrator and share the necessary [err
- Confirm [Cloudflare IP addresses](https://www.cloudflare.com/ips) are not blocked or rate limited.
- Allow all [Cloudflare IP ranges](https://www.cloudflare.com/ips) in your origin web server's firewall or other security software.
- Confirm that — if you have your **SSL/TLS mode** set to **Full** or **Full (Strict**) — your origin supports HTTPS and/or you have installed a [Cloudflare Origin Certificate](/ssl/origin-configuration/origin-ca) or a certificate matching the [requirements for these modes](/ssl/origin-configuration/ssl-modes/#custom-ssltls).
- Find additional troubleshooting information on the [Cloudflare Community](https://community.cloudflare.com/t/community-tip-fixing-error-521-web-server-is-down/42461).
- Find additional troubleshooting information on the [Cloudflare Community](https://community.cloudflare.com/t/community-tip-fixing-error-521-web-server-is-down/42461).