HTTP 101 Switching Protocols vs 421 Misdirected Request
HTTP 101 (Switching Protocols) is a 1xx Informational response, while 421 (Misdirected Request) is a 4xx Client Error response. 101 indicates that the server understands the Upgrade header field request and indicates which protocol it is switching to. 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.
描述
The server understands the Upgrade header field request and indicates which protocol it is switching to.
何时出现
When upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
如何修复
This is normal behavior during protocol upgrades. Ensure your client supports the target protocol.
描述
The request was directed at a server that is unable to produce a response for the combination of scheme and authority in the URI.
何时出现
With HTTP/2 when a connection is reused for a domain the certificate doesn't cover.
如何修复
Retry the request on a new connection.
主要区别
101 is a 1xx Informational response, while 421 is a 4xx Client Error response.
HTTP 101: The server understands the Upgrade header field request and indicates which protocol it is switching to.
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 101 when when upgrading from HTTP/1.1 to WebSocket, or to HTTP/2.
You encounter 421 when with HTTP/2 when a connection is reused for a domain the certificate doesn't cover.
何时使用哪个
For 101 (Switching Protocols): This is normal behavior during protocol upgrades. Ensure your client supports the target protocol. For 421 (Misdirected Request): Retry the request on a new connection.