Unable to patch RHEL 7 WS

This morning I am suddenly unable to patch one of our RHEL 7 Workstation systems. The 'yum update' command is saying "One of the configured repositories failed (Unknown)", followed by some suggestions for what to do, and finally, "file is encrypted or is not a database".

By using a combination of --disablerepo=* and --enablerepo=, it appears to be the rhel-7-workstation-rpms repo that is causing the error. I have tried all of the following with no success: 'yum clean headers', 'yum clean all', and rebuilding the RPM db. I have also verified that the system is properly subscribed.

Any suggestions?

Matt