HTTP 102 Processing vs 521 Web Server Is Down
HTTP 102 (Processing) is a 1xx Informational response, while 521 (Web Server Is Down) is a 5xx Server Error response. 102 indicates that the server has received and is processing the request, but no response is available yet. Prevents the client from timing out. In contrast, 521 means that cloudflare-specific. The origin server refused the connection.
Description
The server has received and is processing the request, but no response is available yet. Prevents the client from timing out.
When You See It
During long-running WebDAV operations.
How to Fix
Wait for the final response. This is an interim status to prevent timeouts.
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.
Key Differences
102 is a 1xx Informational response, while 521 is a 5xx Server Error response.
HTTP 102: The server has received and is processing the request, but no response is available yet. Prevents the client from timing out.
HTTP 521: Cloudflare-specific. The origin server refused the connection.
You encounter 102 when during long-running WebDAV operations.
You encounter 521 when when Cloudflare can't establish a TCP connection to the origin server.
When to Use Which
For 102 (Processing): Wait for the final response. This is an interim status to prevent timeouts. For 521 (Web Server Is Down): Check that the origin server is running and the firewall allows Cloudflare IPs.