今天在.net4.5环境下用WebClient下载https的文件时，报错： 基础连接已经关闭: 发送时发生错误。
加上ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;后正常。
using (WebClient client = new WebClient())
{
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
client.DownloadFile(url, fullName);
}
先记录一下；以后遇到再加上其他情况。
标签：C#,ServicePointManager,下载,https,SecurityProtocol,WebClient,Tls12 From： https://www.cnblogs.com/yellow3gold/p/17013082.html