C# HttpWebResponse WebClient 基礎連接已經關閉: 發送時發生錯誤.

https://blog.csdn.net/sun49842566/article/details/82802297

 

    net 4.0 設置： ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;
    //.net 4.5 設置： ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls1.2;
     

 

附上官方說明

https://docs.microsoft.com/zh-cn/dotnet/api/system.net.securityprotocoltype?view=netframework-4.7.2