ERROR_WINHTTP_CLIENT_AUTH_CERT_NEEDED

Returned by [**WinHttpReceiveResponse**](https://learn.microsoft.com/en-us/windows/desktop/api/Winhttp/nf-winhttp-winhttpreceiveresponse) when the server requests client authentication.

Matched as: the code as given (hex)

Returned by WinHttpReceiveResponse when the server requests client authentication.

Windows Server 2003 with SP1 and Windows XP with SP2: This error is not supported.

Other names

• ERROR_INTERNET_CLIENT_AUTH_CERT_NEEDED: The server is requesting client authentication.

Source: WinHTTP Error Messages · CC-BY-4.0 (MicrosoftDocs/sdk-api, repo license verified 2026-10-09) · retrieved 2026-10-09