421 Misdirected Request
HTTP response status code 421 Misdirected Request is returned by the server to indicate that it has received a request that was not intended for it. This status code was introduced in HTTP/2.
The response is cacheable by default. If the default behavior needs to be overridden then the response must include the appropriate HTTP caching headers.
When the 421 Misdirected Request error message is received, it indicates that the server is unable to produce a response. This status may be sent as a result of connection reuse, where the server does not want clients to reuse connections. In response, a client can try to resubmit the request over a different connection.
This may also occur when an alternative service (Alt-Svc) is selected.
This status will not be generated by proxies.
Search engines like Google will not index a URL with 421 Misdirected Request response status, and consequently, URLs that have been indexed in the past but are now returning this HTTP status code will be removed from the search results.
In the example, the client requests a resource and the server responds with the 421 Misdirected Request error message because it has received a request that was not intended for it.
GET /tech-news HTTP/2
HTTP/2 421 Misdirected Request
Apache HttpComponents Core
The 421 Misdirected Request status code is a client error sent by a server that is unable to produce a response. The client may retry the request using another connection.