HTTP 103 Early Hints vs 521 Web Server Is Down
HTTP 103 (Early Hints) is a 1xx Informational response, while 521 (Web Server Is Down) is a 5xx Server Error response. 103 indicates that used to return some response headers before the final HTTP message. Allows the browser to start preloading resources while the server prepares the response. In contrast, 521 means that cloudflare-specific. The origin server refused the connection.
描述
Used to return some response headers before the final HTTP message. Allows the browser to start preloading resources while the server prepares the response.
何时出现
When a server wants the browser to start loading CSS/JS before the full response is ready.
如何修复
No fix needed. This optimization helps speed up page loading.
描述
Cloudflare-specific. The origin server refused the connection.
何时出现
When Cloudflare can't establish a TCP connection to the origin server.
如何修复
Check that the origin server is running and the firewall allows Cloudflare IPs.
主要区别
103 is a 1xx Informational response, while 521 is a 5xx Server Error response.
HTTP 103: Used to return some response headers before the final HTTP message. Allows the browser to start preloading resources while the server prepares the response.
HTTP 521: Cloudflare-specific. The origin server refused the connection.
You encounter 103 when when a server wants the browser to start loading CSS/JS before the full response is ready.
You encounter 521 when when Cloudflare can't establish a TCP connection to the origin server.
何时使用哪个
For 103 (Early Hints): No fix needed. This optimization helps speed up page loading. For 521 (Web Server Is Down): Check that the origin server is running and the firewall allows Cloudflare IPs.