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HTTP Status Code
421 Misdirected Request
Client ErrorThe request was directed at a server that is not able to produce a response for the given origin.
HTTP status code reference, response example, common causes, fixes, and related status codes.
What does HTTP 421 Misdirected Request mean?
HTTP 421 Misdirected Request is a status code sent by a server to indicate the result of an HTTP request.
Status codes help browsers, APIs, apps, and backend systems understand whether a request succeeded, failed, was redirected, or needs additional action.
In practice, HTTP 421 Misdirected Request usually appears when a server responds under specific request, validation, permission, or infrastructure conditions.
Response example
HTTP/1.1 421 Misdirected Request
HTTP example
HTTP/1.1 421 Misdirected Request
Common causes
- HTTP/2 connection reuse targeting the wrong origin
- Request routed to a server not configured for the requested host
- Misconfigured load balancer or SNI mismatch
How to fix it
- Open a new connection to the correct server
- Check load balancer routing and SNI configuration
- Verify virtual host configuration on the server
Common mistakes
- Assuming the status code alone explains the full backend issue
- Ignoring related response headers that add important context
- Treating temporary errors as permanent failures
- Retrying too aggressively without checking the cause
- Debugging the frontend only when the problem is server-side
How browsers and APIs use it
Browsers, APIs, and backend services use HTTP status codes to understand the outcome of a request. Depending on the status code, an application may render content, retry a request, redirect the user, show an error, or trigger a different flow in the client or server.
Practical developer insight
421 is defined in RFC 9110 and is primarily seen in HTTP/2 connection reuse scenarios where a request is accidentally routed to the wrong server. Clients should retry the request on a fresh connection.
Client-side example
if (response.status === 421) {
console.warn("Misdirected request — retrying on a new connection.");
}