IIS中.NET网站The underlying connection was closed: An unexpected error occurred on a reception错误的处理方式

网站程序中请求别的API地址报错：The underlying connection was closed: An unexpected error occurred on a reception

百度了一下，说是服务器请求HTTPS资源时的安全问题。解决方法是在代码中发送请求前加入下面的代码

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;//这个是单独加的代码

WebRequest HttpWebRequest = WebRequest.Create(Url);