The SSL connection could not be established

I'm also getting this "The context has expired and can no longer be used" exception from a .NET application that's authenticating against an API using mTLS. The certificate being attached to the request is read off of a smart card. ...on the call to HttpClient.GetAsync.

The API hits worked about 10 times during testing in my dev environment before getting the error. Using a browser works.

I've tried and failed to learn what context is being referred to. Is it an HttpClient HttpContext? An SslStream TransportContext?

string responseBody;
X509Certificate2 smartCardCertificate = GetSmartCardCertificate();

using (var httpClientHandler = new HttpClientHandler())
{
    httpClientHandler.ClientCertificates.Add(smartCardCertificate);
    httpClientHandler.ClientCertificateOptions = ClientCertificateOption.Manual;
    httpClientHandler.SslProtocols = SslProtocols.None;

    using (var httpClient = new HttpClient(httpClientHandler))
    {
        HttpResponseMessage response;

        response = await httpClient.GetAsync(my_special_url);
        response.EnsureSuccessStatusCode();

        responseBody = await response.Content.ReadAsStringAsync();
    }
}