title: AWS API Gateway gives 'More than one client certificate passed' error
body: <p>I have set up Mutual TLS authentication for my API Gateway.
  I then placed my client certificate in the truststore. The file contains the client certificate, intermediate and root certificates (private CA).</p>
  <p>When accessing the API Gateway with a browser (Chrome on Windows), browser asks me to provide client certificate. I select the same certificate as I have placed in the trust store.</p>
  <p>API Gateway reports the following in the browser:</p>
  <p>{&quot;message&quot;:&quot;Invalid client certificate chain. More than one client certificate passed&quot;}</p>
  <p>UPDATE: I have also tried placing only intermediate and root certs in the trust store. Same error.</p>
  <p>UPDATE 2: The same error is also reported when accessing the API with C# code (WebClient) loading the cert from Windows cert store or from disc (pfx file).</p>