The request was directed at a server that is not able to produce a response. This can be sent by a server that is not configured to produce responses for the combination of scheme and authority that are included in the request URI.
Clients receiving a 421 Misdirected Request response from a server MAY retry the request -- whether the request method is idempotent or not -- over a different connection. This is possible if a connection is reused<sup>[1](#ref-1)</sup>or if an alternative service is selected [ALT-SVC][3].