C# Core 3.1 - 调用 HttpClient SendAsync() 时收到错误消息“无法建立 SSL 连接”

环境：控制台应用程序，C# Core 3.1，VS 2019

我正在执行以下行：

var response = await client.SendAsync(request).ConfigureAwait(false);

我收到以下错误：

{"The SSL connection could not be established, see inner exception."}
    Data: {System.Collections.ListDictionaryInternal}
    HResult: -2146233087
    HelpLink: null
    InnerException: {"Authentication failed, see inner exception."}
    Message: "The SSL connection could not be established, see inner exception."
    Source: "System.Net.Http"
    StackTrace: "   at System.Net.Http.ConnectHelper.<EstablishSslConnectionAsyncCore>d__4.MoveNext()\r\n   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()\r\n   at ...

做了一些谷歌搜索并发现了这个：

https://github.com/dotnet/runtime/issues/28189

所以我添加了

AppContext.SetSwitch("System.Net.Http.UseSocketsHttpHandler", false);

就在上面那行之前。仍然收到错误。

在执行行之前我有一堆代码：

httpClientHandler = new HttpClientHandler
{
    SslProtocols = SslProtocols.Tls12
};

添加用于添加证书、标头、内容类型等的代码。不确定到底是什么导致了错误。有任何想法吗？

Thanks,