HTTP 103 Early Hints vs 502 Bad Gateway
HTTP 103 (Early Hints) is a 1xx Informational response, while 502 (Bad Gateway) 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, 502 means that the server, acting as a gateway or proxy, received an invalid response from the upstream server.
Description
Used to return some response headers before the final HTTP message. Allows the browser to start preloading resources while the server prepares the response.
When You See It
When a server wants the browser to start loading CSS/JS before the full response is ready.
How to Fix
No fix needed. This optimization helps speed up page loading.
Description
The server, acting as a gateway or proxy, received an invalid response from the upstream server.
When You See It
When Nginx/Apache can't reach the application server (e.g., Gunicorn is down, upstream timeout).
How to Fix
Check if the upstream server is running. Verify proxy configuration. Check for upstream timeouts.
Key Differences
103 is a 1xx Informational response, while 502 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 502: The server, acting as a gateway or proxy, received an invalid response from the upstream server.
You encounter 103 when when a server wants the browser to start loading CSS/JS before the full response is ready.
You encounter 502 when when Nginx/Apache can't reach the application server (e.g., Gunicorn is down, upstream timeout).
When to Use Which
For 103 (Early Hints): No fix needed. This optimization helps speed up page loading. For 502 (Bad Gateway): Check if the upstream server is running. Verify proxy configuration. Check for upstream timeouts.