您应该抛出一个Htt$p$psponseException$c$c>从您的API方法，而不是HttpException$c$c>:

You should be throwing a HttpResponseException from your API method, not HttpException:

throw new HttpResponseException(HttpStatusCode.Unauthorized);

或者，如果你想提供一个自定义消息：

Or, if you want to supply a custom message:

var msg = new HttpResponseMessage(HttpStatusCode.Unauthorized) { ReasonPhrase = "Oops!!!" };
throw new HttpResponseException(msg);