该请求被中止：无法在CSOM中创建SSL/TLS安全通道

Question

在以下错误之下，请建议任何解决方案。

该请求被中止：无法在Windows Server2012 R2上创建SSL/TLS Secure Channel 。在ClientContext.executequery上。

CSOM SharePoint的代码：

ServicePointManager.Expect100Continue = true;
            ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
                   | SecurityProtocolType.Tls11
                   | SecurityProtocolType.Tls12
                   | SecurityProtocolType.Ssl3;

using (ClientContext ctx = new ClientContext("test.SharePoint.Com"))
            {

                try
                {
                    ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;

                    ctx.AuthenticationMode = ClientAuthenticationMode.Default;
                    SecureString securePassword = new SecureString();
                    foreach (char c in "test")
                        securePassword.AppendChar(c);

                    ctx.Credentials = new SharePointOnlineCredentials("test.com", securePassword);
                    Web web = ctx.Web;
                    ctx.Load(web);
                    ctx.ExecuteQuery(); //The request was aborted: Could not create SSL/TLS secure channel.
                    Console.WriteLine("The web site title: " + web.Title);
                    Console.Read();
                }
                catch(Exception ex)
                {
                    Console.WriteLine(ex.Message);
                }
            }

谢谢。