Other 4xx codes
All HTTP status codes in ASP.NET Core
4xx Client error
499 Client Closed Request
Not a standard code. nginx logs it when the client disconnects before the response; it is never sent to the client.
In ASP.NET Core: StatusCodes has a constant for it, useful for logging cancelled requests (HttpContext.RequestAborted).
499 in .NET
The StatusCodes constant, HttpStatusCode enum name, reason phrase, class, and how EnsureSuccessStatusCode() and the standard resilience handler treat 499.
| Constant | StatusCodes.Status499ClientClosedRequest |
|---|---|
| HttpStatusCode | none; use (HttpStatusCode)499 |
| Reason phrase | Kestrel sends Client Closed Request; HttpClient's ReasonPhrase is null |
| Class | 4xx, client error |
| IsSuccessStatusCode | false |
| EnsureSuccessStatusCode() | throws HttpRequestException: Response status code does not indicate success: 499. |
| Standard resilience handler | does not retry it |
Returning 499
Minimal APIs
Results.StatusCode(StatusCodes.Status499ClientClosedRequest)
Results.Problem(statusCode: StatusCodes.Status499ClientClosedRequest, detail: "...")Controllers
StatusCode(StatusCodes.Status499ClientClosedRequest)
Problem(statusCode: StatusCodes.Status499ClientClosedRequest, detail: "...")The ProblemDetails body
What Results.Problem(statusCode: 499) sends (with AddProblemDetails()), as application/problem+json:
{
"title": "Client Closed Request",
"status": 499,
"traceId": "0HNA1B2C3D4E5:00000001"
}A controller's Problem(statusCode: 499) sends a different body, because MVC only fills type and title for codes in ApiBehaviorOptions.ClientErrorMapping:
{
"status": 499,
"traceId": "0HNA1B2C3D4E5:00000001"
}A bare StatusCode(499) in an [ApiController] also gets a ProblemDetails body automatically; Results.StatusCode(499) 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.