[转][C#]基础连接已经关闭 未能为 SSL/TLS 安全通道建立信任关系

来自：https://www.cnblogs.com/waw/p/8286608.html

代码部分：

static TestApplication(){
    ServicePointManager.ServerCertificateValidationCallback += RemoteCertificateValidate;
}

ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(remoteCertificateValidate);
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls | SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11; 

private static bool RemoteCertificateValidate(object sender, X509Certificate cert, X509Chain chain, SslPolicyErrors error)
{
    //为了通过证书验证，总是返回true
    return true;
}

 第二段代码要求  .net 4.5.2 或更高版本。