.NET Framework服务HTTP请求异常：UTF-8不是有效编码名称

在.NET Framework服务中发起HTTP请求时，多数客户端运行正常，但特定场景下抛出异常。转译后的错误信息为：

"The character set provided in the ContentType is invalid."……"UTF-8 is not a valid encoding name."

相关代码片段：

requestMessage.Content = new System.Net.Http.StringContent(json, Encoding.UTF8, "application/json");

TaskAwaiter<HttpResponseMessage> response;
try
{
    response = HTTPClient.SendAsync(requestMessage).GetAwaiter();
}
catch (Exception e)
{
    throw new CDBAPIException($"Falha POST {url}", e);
}
try
{
    var result = response.GetResult();
    if (result.StatusCode != System.Net.HttpStatusCode.OK)
    {
        throw new CDBAPIException($"Falha POST {result.StatusCode} - {result.ReasonPhrase}");
    }

    var content = response.GetResult().Content.ReadAsStringAsync().GetAwaiter();
    dynamic updates = JsonConvert.DeserializeObject(content.GetResult());
}

• 显式指定带字符集的ContentType
  直接在ContentType中明确添加charset=utf-8，避免框架在特定环境下对编码名称的解析偏差：

  requestMessage.Content = new System.Net.Http.StringContent(json, Encoding.UTF8, "application/json; charset=utf-8");
  

• 手动注册编码提供者
  若服务器本地化配置异常，可能导致系统未正确注册UTF-8编码。可在程序启动时手动注册编码：

  Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
  

  注意需先安装System.Text.Encoding.CodePages NuGet包。

• 优化重复调用问题
  原代码中多次调用response.GetResult()属于冗余操作，建议缓存结果避免潜在风险：

  var result = response.GetResult();
  if (result.StatusCode != System.Net.HttpStatusCode.OK)
  {
      throw new CDBAPIException($"Falha POST {result.StatusCode} - {result.ReasonPhrase}");
  }
  
  var content = result.Content.ReadAsStringAsync().GetAwaiter();
  dynamic updates = JsonConvert.DeserializeObject(content.GetResult());
  

内容的提问来源于stack exchange，提问作者Ferri16