//1.
ServicePointManager.ServerCertificateValidationCallback = (sender, certificate, chain, sslPolicyErrors) => true;
//2.
ServicePointManager.ServerCertificateValidationCallback = new
RemoteCertificateValidationCallback
(
delegate { return true; }
);
基础连接已经关闭: 未能为 SSL/TLS 安全通道建立信任关系
原文：http://www.cnblogs.com/XuPengLB/p/5724802.html