HTTP 200 OK vs 521 Web Server Is Down
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HTTP 200 (OK) is a 2xx Success response, while 521 (Web Server Is Down) is a 5xx Server Error response. 200 indicates that the request succeeded. The meaning depends on the HTTP method: GET returns the resource, POST reports the action result, HEAD returns headers only. In contrast, 521 means that cloudflare-specific. The origin server refused the connection.
Description
The request succeeded. The meaning depends on the HTTP method: GET returns the resource, POST reports the action result, HEAD returns headers only.
When You See It
The most common HTTP response — indicates the request was processed successfully.
How to Fix
No fix needed. The request succeeded as expected.
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
200 is a 2xx Success response, while 521 is a 5xx Server Error response.
HTTP 200: The request succeeded. The meaning depends on the HTTP method: GET returns the resource, POST reports the action result, HEAD returns headers only.
HTTP 521: Cloudflare-specific. The origin server refused the connection.
You encounter 200 when the most common HTTP response — indicates the request was processed successfully.
You encounter 521 when when Cloudflare can't establish a TCP connection to the origin server.
When to Use Which
For 200 (OK): No fix needed. The request succeeded as expected. For 521 (Web Server Is Down): Check that the origin server is running and the firewall allows Cloudflare IPs.