HTTP 100 Continue vs 421 Misdirected Request
HTTP 100 (Continue) is a 1xx Informational response, while 421 (Misdirected Request) 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, 421 means that the request was directed at a server that is unable to produce a response for the combination of scheme and authority in the URI.
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 request was directed at a server that is unable to produce a response for the combination of scheme and authority in the URI.
Cuándo lo verás
With HTTP/2 when a connection is reused for a domain the certificate doesn't cover.
Cómo solucionarlo
Retry the request on a new connection.
Diferencias clave
100 is a 1xx Informational response, while 421 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 421: The request was directed at a server that is unable to produce a response for the combination of scheme and authority in the URI.
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 421 when with HTTP/2 when a connection is reused for a domain the certificate doesn't cover.
Cuándo usar cada uno
For 100 (Continue): This is an interim response — no fix needed. The client should continue sending the request body. For 421 (Misdirected Request): Retry the request on a new connection.