HTTP 100 Continue vs 426 Upgrade Required
HTTP 100 (Continue) is a 1xx Informational response, while 426 (Upgrade Required) is a 4xx Client Error response. 100 indicates that the server has received the request headers and the client should proceed to send the request body. This lets the client know it can continue with the request or abort if the headers were rejected. 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.
Descripción
The server has received the request headers and the client should proceed to send the request body. This lets the client know it can continue with the request or abort if the headers were rejected.
Cuándo lo verás
When a client sends an Expect: 100-continue header, the server responds with 100 before the client sends the body.
Cómo solucionarlo
This is an interim response — no fix needed. The client should continue sending the request body.
Descripción
The server refuses to perform the request using the current protocol but might after the client upgrades to a different protocol.
Cuándo lo verás
When a server requires HTTPS or a newer protocol version.
Cómo solucionarlo
Switch to the protocol specified in the Upgrade response header.
Diferencias clave
100 is a 1xx Informational response, while 426 is a 4xx Client Error response.
HTTP 100: The server has received the request headers and the client should proceed to send the request body. This lets the client know it can continue with the request or abort if the headers were rejected.
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 100 when when a client sends an Expect: 100-continue header, the server responds with 100 before the client sends the body.
You encounter 426 when when a server requires HTTPS or a newer protocol version.
Cuándo usar cada uno
For 100 (Continue): This is an interim response — no fix needed. The client should continue sending the request body. For 426 (Upgrade Required): Switch to the protocol specified in the Upgrade response header.