New Kubernetes Cluster: remote error: tls: bad certificate
From the documentation you linked, it states,


  The referenced file must contain one or more certificates authorities to use to validate client certificates presented to the API server.


This means your client's certificate is invalid because either:


The server doesn't trust the client's signing certificate authority
The client doesn't trust the server's signing certificate authority
The certificate's DN doesn't match the hostname


The most likely scenario is that 1. The server doesn't trust the client's signing certificate authority since the server doesn't verify DNS for the client certificate and the error indicates this is a remote error not on the client. Most likely this means the client's certificate was signed on the client itself, not on the server.

You will need to make sure to generate the certificate on the client, have the server sign it and then transfer the certificate back to the client. Otherwise, you need to add the server's CA certificate to the Client's keystore.. You can ensure you do not have a DNS/DN mismatch by setting hosts file entries.