不幸的是，我在插件中开发这个功能的整个过程中一直在运行Fiddler，自从部署到客户端后，我发现它对任何人都不起作用--除非他们也运行Fiddler！如果我停止运行Fiddler，它在我的开发机器上也不起作用。
主要错误是Error while copying content to a stream.。（对我来说，这解释了为什么运行Fiddler解决了这个问题-因为我相信请求会首先发送给Fiddler，然后Fiddler将其发送到服务器）。然而，我找不到任何东西来支持这可能是问题所在。我已经尝试确保它保存数据，但我没有。我觉得我走的路不对。
代码大致如下：

HttpClientHandler httpHandler = new HttpClientHandler { UseDefaultCredentials = true };
var client = new HttpClient(httpHandler, false);
client.BaseAddress = new Uri(BaseUrl + "api/job/PostTest");

var content = new MultipartFormDataContent("Upload----" + DateTime.Now.ToString(System.Globalization.CultureInfo.InvariantCulture));

content.Add(new StringContent(mailItem.HTMLBody, Encoding.UTF8), "BodyHtml");
// content.Add()'s... Omitted for brevity

var response = client.PostAsync(BaseUrl + "api/job/PostTest", content);

response.ContinueWith(prevTask => {

    if (prevTask.Result.IsSuccessStatusCode)
    {
        System.Diagnostics.Debug.WriteLine("Was success");
    }
    else
    {
        System.Diagnostics.Debug.WriteLine("Was Error");
    }

}, System.Threading.Tasks.TaskContinuationOptions.OnlyOnRanToCompletion);


response.ContinueWith(prevTask =>{
    MessageBox.Show(prevTask.Exception.ToString());
}, System.Threading.Tasks.TaskContinuationOptions.OnlyOnFaulted);

完整的例外详细信息为：

System.AggregateException: One or more errors occurred. ---> System.Net.Http.HttpRequestException: Error while copying content to a stream. ---> System.IO.IOException: The read operation failed, see inner exception. ---> System.Net.WebException: The request was aborted: The request was canceled.
   at System.Net.ConnectStream.BeginRead(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
   at System.Net.Http.HttpClientHandler.WebExceptionWrapperStream.BeginRead(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state)
   --- End of inner exception stack trace ---
   at System.Net.Http.HttpClientHandler.WebExceptionWrapperStream.BeginRead(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state)
   at System.Net.Http.StreamToStreamCopy.StartRead()
   --- End of inner exception stack trace ---
   --- End of inner exception stack trace ---
---> (Inner Exception #0) System.Net.Http.HttpRequestException: Error while copying content to a stream. ---> System.IO.IOException: The read operation failed, see inner exception. ---> System.Net.WebException: The request was aborted: The request was canceled.
   at System.Net.ConnectStream.BeginRead(Byte[] buffer, Int32 offset, Int32 size, AsyncCallback callback, Object state)
   at System.Net.Http.HttpClientHandler.WebExceptionWrapperStream.BeginRead(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state)
   --- End of inner exception stack trace ---
   at System.Net.Http.HttpClientHandler.WebExceptionWrapperStream.BeginRead(Byte[] buffer, Int32 offset, Int32 count, AsyncCallback callback, Object state)
   at System.Net.Http.StreamToStreamCopy.StartRead()
   --- End of inner exception stack trace ---<---

如果有人能给我指出一些对我有帮助的资源，或者指出我哪里出错了，那将有很大的帮助！