HTTP 206 Partial Content vs 521 Web Server Is Down
HTTP 206 (Partial Content) is a 2xx Success response, while 521 (Web Server Is Down) is a 5xx Server Error response. 206 indicates that the server is delivering only part of the resource due to a Range header sent by the client. Used for resumable downloads and video streaming. In contrast, 521 means that cloudflare-specific. The origin server refused the connection.
Description
The server is delivering only part of the resource due to a Range header sent by the client. Used for resumable downloads and video streaming.
When You See It
During video streaming, large file downloads, or when resuming interrupted downloads.
How to Fix
No fix needed. This is normal behavior for range requests.
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
206 is a 2xx Success response, while 521 is a 5xx Server Error response.
HTTP 206: The server is delivering only part of the resource due to a Range header sent by the client. Used for resumable downloads and video streaming.
HTTP 521: Cloudflare-specific. The origin server refused the connection.
You encounter 206 when during video streaming, large file downloads, or when resuming interrupted downloads.
You encounter 521 when when Cloudflare can't establish a TCP connection to the origin server.
When to Use Which
For 206 (Partial Content): No fix needed. This is normal behavior for range requests. For 521 (Web Server Is Down): Check that the origin server is running and the firewall allows Cloudflare IPs.