HTTP 103 Early Hints vs 412 Precondition Failed
HTTP 103 (Early Hints) is a 1xx Informational response, while 412 (Precondition Failed) is a 4xx Client 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, 412 means that one or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
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
One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
When You See It
When using conditional requests with ETags and the resource has changed.
How to Fix
Refresh the ETag/Last-Modified value and retry with updated preconditions.
Key Differences
103 is a 1xx Informational response, while 412 is a 4xx Client 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 412: One or more conditions in the request headers (If-Match, If-Unmodified-Since) evaluated to false.
You encounter 103 when when a server wants the browser to start loading CSS/JS before the full response is ready.
You encounter 412 when when using conditional requests with ETags and the resource has changed.
When to Use Which
For 103 (Early Hints): No fix needed. This optimization helps speed up page loading. For 412 (Precondition Failed): Refresh the ETag/Last-Modified value and retry with updated preconditions.