The SSL connection could not be established when using httpclient in c# (.net core) but works in Postman and Browser

Question

I have a .net core console app with a function that will do a simple http call and get the page content (this is for a testing). I am getting an issue "The SSL connection could not be established". But when I try the same url with Postman or a browser it works fine. Can anyone help me on this?

inner exception:"Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.."

private static async Task<string> CallUrl(string url)
{
   using var client = new HttpClient();
   using var response = await client.GetAsync(url);
   using var content = response.Content;
   var data = await content.ReadAsStringAsync();
   return data;
}

I tried the suggestion in The SSL connection could not be established as well. like this but no luck.

  private static async Task<string> CallUrl(string url)
  {
    var clientHandler = new HttpClientHandler
    {
       ServerCertificateCustomValidationCallback = (sender, cert, chain, sslPolicyErrors) =>
       {
           return true;
       }
    };
    using var client = new HttpClient(clientHandler);
    using var response = await client.GetAsync(url);
    using var content = response.Content;
    var data = await content.ReadAsStringAsync();
    return data;
  }

Answer 1

我在调用 web 服务时遇到了同样的问题，我能够在 IIS AppPool 高级属性上修复更新“加载用户配置文件”= true