When running CA Access Gateway (SPS), after having changed a
partnership certificate, the partnership doesn't work anymore and
requests are failing.
CA Access Gateway (SPS) 12.8SP6 on Windows;
Share the certificate with the SP Partner, directly by sending the
certificate and keys, or sharing the updated Metadata with them to
solve the issue.
Federation certificates are totally different than SSL (https)
certificates, and they aren't related one to the other.