HTTP 103 Early Hints vs 426 Upgrade Required
HTTP 103 (Early Hints) is a 1xx Informational response, while 426 (Upgrade Required) 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, 426 means that the server refuses to perform the request using the current protocol but might after the client upgrades to a different protocol.
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 refuses to perform the request using the current protocol but might after the client upgrades to a different protocol.
When You See It
When a server requires HTTPS or a newer protocol version.
How to Fix
Switch to the protocol specified in the Upgrade response header.
Key Differences
103 is a 1xx Informational response, while 426 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 426: The server refuses to perform the request using the current protocol but might after the client upgrades to a different protocol.
You encounter 103 when when a server wants the browser to start loading CSS/JS before the full response is ready.
You encounter 426 when when a server requires HTTPS or a newer protocol version.
When to Use Which
For 103 (Early Hints): No fix needed. This optimization helps speed up page loading. For 426 (Upgrade Required): Switch to the protocol specified in the Upgrade response header.