Other 4xx codes
All HTTP status codes in ASP.NET Core
4xx Client error
421 Misdirected Request
The request reached a server that cannot answer for this host, typically over a reused HTTP/2 connection.
In ASP.NET Core: Sent by servers and load balancers, not by application code.
421 in .NET
The StatusCodes constant, HttpStatusCode enum name, reason phrase, class, and how EnsureSuccessStatusCode() and the standard resilience handler treat 421.
| Constant | StatusCodes.Status421MisdirectedRequest |
|---|---|
| HttpStatusCode | HttpStatusCode.MisdirectedRequest |
| Reason phrase | Kestrel sends Misdirected Request |
| Class | 4xx, client error |
| IsSuccessStatusCode | false |
| EnsureSuccessStatusCode() | throws HttpRequestException: Response status code does not indicate success: 421 (Misdirected Request). |
| Standard resilience handler | does not retry it |
Returning 421
Minimal APIs
Results.StatusCode(StatusCodes.Status421MisdirectedRequest)
Results.Problem(statusCode: StatusCodes.Status421MisdirectedRequest, detail: "...")Controllers
StatusCode(StatusCodes.Status421MisdirectedRequest)
Problem(statusCode: StatusCodes.Status421MisdirectedRequest, detail: "...")The ProblemDetails body
What Results.Problem(statusCode: 421) sends (with AddProblemDetails()), as application/problem+json:
{
"type": "https://tools.ietf.org/html/rfc9110#section-15.5.20",
"title": "Misdirected Request",
"status": 421,
"traceId": "0HNA1B2C3D4E5:00000001"
}A controller's Problem(statusCode: 421) sends the same body.
A bare StatusCode(421) in an [ApiController] also gets a ProblemDetails body automatically; Results.StatusCode(421) in a minimal API sends an empty body unless you add UseStatusCodePages().
Every response on this page was recorded from ASP.NET Core 10.0.12 on Kestrel in the Production environment; the HttpClient rows come from .NET 10.0.12 and Microsoft.Extensions.Http.Resilience 10.10.0.