c# - 带有 xml 正文的 HttpClient postAsync 以 BadRequest 错误结尾

Question

我想将 xml 字符串消息发布到服务器，但它以错误的请求结束。似乎是一个非常简单但不明白我在做什么的错误？

请帮忙。:(

msgXML 是一个字符串化的 xml

 public static async Task<string> SendMessageAsync(string msgXml)
 {
  using (CancellationTokenSource source = new CancellationTokenSource())
  {
    CancellationToken cancellation = source.Token;
    HttpClient client = HttpClientProvider.GetInstance;
    //client.BaseAddress = new Uri(myUri);
    client.DefaultRequestHeaders.Accept.Add(new 
    MediaTypeWithQualityHeaderValue("application/xml"));
    client.DefaultRequestHeaders.Add("X-HTTP-Dest-Address", destinationAddress);
    client.DefaultRequestHeaders.TryAddWithoutValidation("Content-Type", "application/xml;charset=utf-8");
    var httpContent = new StringContent(msgXml, Encoding.UTF8, "application/xml");

    HttpResponseMessage httpResponse = await client.PostAsync(myUri, httpContent, cancellationToken).ConfigureAwait(false);
    if (!httpResponse.IsSuccessStatusCode)
     {
       throw new Exception("Invalid URI");
     }
  }
}

我的 msgXML：

<MSG>
 <HeaderCommon>
  other elements....
  <payload></payload>
 </HeaderCommon>
</MSG>

我得到的错误只是：

    ReasonPhrase: "Bad Request"
    statusCode: 400

服务器不安全（http）。