421 Misdirected Request

Usage

The 421 Misdirected Request error indicates the server is unable to produce a response. This status is sent as a result of connection reuse, where the server does not want clients to reuse connections. In response, a client tries to resubmit the request over a different connection.

This also occurs when an alternative service (Alt-Svc) is selected.

This status will not be generated by proxies.

Example

The client requests a resource and the server responds with 421 Misdirected Request because the request arrived on a connection not intended for this host.

Request

GET /tech-news HTTP/2
Host: example.com

Response

HTTP/2 421 Misdirected Request

How to fix

Retry the request on a new, dedicated connection to the intended origin. The browser or client opens a fresh TCP/TLS session rather than reusing an existing HTTP/2 multiplexed connection.

On the server side, verify the TLS certificate covers every hostname the server handles. A mismatch between the SNI (Server Name Indication) value and the Host header is the most common trigger.

When nginx reverse-proxies to an Apache backend over HTTPS, enable SNI forwarding so Apache sees the correct hostname:

In Apache, confirm each virtual host has a matching ServerName and a valid certificate. Tightened SNI checks in recent Apache releases reject requests where the SNI hostname and the Host header conflict.

For CDNs and load balancers re-encrypting traffic to the origin, ensure the upstream TLS handshake sends the correct SNI value. Cloudflare and similar services need the origin certificate to list all served hostnames.

Disable HTTP/2 connection coalescing on the server when multiple domains share an IP but use different certificates. Each domain needs a separate connection.

Code references

.NET

HttpStatusCode.MisdirectedRequest

Rust

http::StatusCode::MISDIRECTED_REQUEST

Rails

:misdirected_request

Go

http.StatusMisdirectedRequest

Symfony

Response::HTTP_MISDIRECTED_REQUEST

Python3.5+

http.HTTPStatus.MISDIRECTED_REQUEST

Apache HttpComponents Core

org.apache.hc.core5.http.HttpStatus.SC_MISDIRECTED_REQUEST

Angular

@angular/common/http/HttpStatusCode.MisdirectedRequest