421 Misdirected Request means the request was sent to a server that is not able or not willing to produce an authoritative response for the target URL. Usually the host name in the request does not match a site the server is configured for, or does not match the connection the request arrived on.
It became common with HTTP/2 and HTTP/3, where browsers reuse one connection for several host names that share an IP address and certificate ("connection coalescing"). If the server cannot serve one of those host names on that connection, it answers 421, and the client retries on a new connection. Clients may retry after a 421 even for non-idempotent methods. Proxies must not generate 421.
Apache httpd also returns 421 when the Host header does not match the TLS Server Name Indication (SNI) of the connection, which often happens when a reverse proxy forwards HTTPS requests to Apache without sending the right SNI.
Example response
HTTP/1.1 421 Misdirected Request
Date: Fri, 06 Nov 2026 10:15:32 GMT
Server: Apache
Content-Type: text/html; charset=iso-8859-1
Content-Length: 321
<!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<html><head>
<title>421 Misdirected Request</title>
</head><body>
<h1>Misdirected Request</h1>
<p>The client needs a new connection for this request as the requested host name does not match the Server Name Indication (SNI) in use for this connection.</p>
</body></html>SEO and redirect checking
Browsers recover from 421 automatically, but crawlers and redirect checkers may report it as a 4xx error, and affected URLs may then not be indexed. If a check returns 421, review the TLS/SNI and virtual host configuration of the server and of any proxy in front of it.
Common causes and use cases
- A reverse proxy connects to an HTTPS backend without SNI or with the wrong SNI. In nginx, enable
proxy_ssl_server_name on. - Several host names share a certificate and an IP address, and a connection is reused for a host the server does not serve on it.
- A virtual host is missing for a host name whose DNS points to the server.