HTTP 521 Web Server Is Down vs 530 Site Frozen
Both HTTP 521 (Web Server Is Down) and 530 (Site Frozen) belong to the 5xx Server Error category. 521 indicates that cloudflare-specific. The origin server refused the connection. Meanwhile, 530 means that cloudflare-specific. Used by Pantheon hosting to indicate a frozen site.
Description
Cloudflare-specific. The origin server refused the connection.
When You See It
When Cloudflare can't establish a TCP connection to the origin server.
How to Fix
Check that the origin server is running and the firewall allows Cloudflare IPs.
Description
Cloudflare-specific. Used by Pantheon hosting to indicate a frozen site.
When You See It
When a site on Pantheon hosting has been frozen due to inactivity.
How to Fix
Reactivate the site on the hosting platform.
Key Differences
HTTP 521: Cloudflare-specific. The origin server refused the connection.
HTTP 530: Cloudflare-specific. Used by Pantheon hosting to indicate a frozen site.
You encounter 521 when when Cloudflare can't establish a TCP connection to the origin server.
You encounter 530 when when a site on Pantheon hosting has been frozen due to inactivity.
When to Use Which
For 521 (Web Server Is Down): Check that the origin server is running and the firewall allows Cloudflare IPs. For 530 (Site Frozen): Reactivate the site on the hosting platform.