如果您是从Visual Studio运行代码，请尝试以管理员身份运行Visual Studio。为我修正了这个问题。

In my case, I was running under Visual Studio 2022. Time and time again I was getting this error. Going through the code I saw that it retrieved the certificate just fine. Security was set to TLS1.2, both answers above. For whatever reason, running Visual Studio as Administrator made it work! Maybe someone can explain to me how the code retrieved the certificate from the store just fine. I could see it and all the properties. Why in the name of this world would it not process the request unless I run VS in admin mode???

我一整天都在为这个问题而挣扎。

当我用。net 4.5创建一个新项目时，我终于让它工作了。

但如果我降级到4.0，我又遇到了同样的问题，而且对于那个项目来说是不可逆转的(即使我试图再次升级到4.5)。

奇怪的是，没有其他错误消息，但“请求被中止:无法创建SSL/TLS安全通道。

这一个是为我工作在MVC webclient

public string DownloadSite(string RefinedLink)
{
    try
    {
        Uri address = new Uri(RefinedLink);

        ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;

        System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls11 | SecurityProtocolType.Tls12;

        using (WebClient webClient = new WebClient())
        {
            var stream = webClient.OpenRead(address);
            using (StreamReader sr = new StreamReader(stream))
            {
                var page = sr.ReadToEnd();

                return page;
            }
        }

    }
    catch (Exception e)
    {
        log.Error("DownloadSite - error Lin = " + RefinedLink, e);
        return null;
    }
}

在Windows Server 2012中，从注册表中删除这个选项对我有帮助 [HKEY_LOCAL_MACHINE \ SYSTEM \ CurrentControlSet \ \ SecurityProviders \ SCHANNEL \ KeyExchangAlgorithms控制

这些答案都不适合我，谷歌chrome和邮递员工作，握手服务器，但ie和。net不工作。在谷歌chrome在安全选项卡>连接显示加密和认证使用ECDHE_RSA与P-256和AES_256_GCM密码套件与服务器握手。

我在windows server 2012 R2上安装了IIS密码和密码套件列表，无法找到带有P-256和AES_256_GCM密码套件的ECDHE_RSA。然后我把Windows更新到上一个版本，但问题没有解决。最后在搜索之后，我明白了windows server 2012 R2不支持GSM，并将我的服务器更新到windows server 2016，我的问题解决了。