DevToolsmith

HTTP 421 Misdirected Request

HTTP 421 Misdirected Request means the request reached a server that can’t answer for that host name. The request contains an error or can’t be fulfilled. Retrying unchanged won’t help.

Class
4xx Client error
Standard
RFC 9110
Cacheable by default
No
Safe to retry
No
Go constant
http.StatusMisdirectedRequest

What HTTP 421 means

With HTTP/2, browsers reuse one connection for several domains that share a certificate and IP address. If the server can’t serve one of those domains on that connection, it returns 421 and the browser retries on a new connection. Misconfigured TLS virtual hosts are the usual cause.

Retrying

No. Fix the request first; sending it again unchanged will get the same response.

Example response

HTTP/1.1 421 Misdirected Request
Date: Wed, 21 Oct 2026 10:30:00 GMT
Content-Type: application/json

How to return 421

Node.js (Express)
res.status(421).json({ error: 'Misdirected Request' });
Python (FastAPI)
from fastapi import HTTPException

raise HTTPException(status_code=421, detail="Misdirected Request")
Go (net/http)
http.Error(w, http.StatusText(http.StatusMisdirectedRequest), http.StatusMisdirectedRequest)
nginx
location /private/ {
    return 421;
}

Related status codes

  • 400 Bad Request : The server can’t process the request because it is malformed.
  • 502 Bad Gateway : A proxy or gateway got an invalid response from the upstream server.

Other 4xx status codes

400 Bad Request · 401 Unauthorized · 402 Payment Required · 403 Forbidden · 404 Not Found · 405 Method Not Allowed · 406 Not Acceptable · 407 Proxy Authentication Required · 408 Request Timeout · 409 Conflict · 410 Gone · 411 Length Required · 412 Precondition Failed · 413 Content Too Large · 414 URI Too Long · 415 Unsupported Media Type · 416 Range Not Satisfiable · 417 Expectation Failed · 418 I’m a Teapot · 422 Unprocessable Content · 423 Locked · 424 Failed Dependency · 425 Too Early · 426 Upgrade Required · 428 Precondition Required · 429 Too Many Requests · 431 Request Header Fields Too Large · 444 No Response · 451 Unavailable For Legal Reasons · 499 Client Closed Request

See the full list of HTTP status codes.

Sources

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Frequently asked questions

What does HTTP 421 Misdirected Request mean?

HTTP 421 Misdirected Request means the request reached a server that can’t answer for that host name. With HTTP/2, browsers reuse one connection for several domains that share a certificate and IP address. If the server can’t serve one of those domains on that connection, it returns 421 and the browser retries on a new connection. Misconfigured TLS virtual hosts are the usual cause.