I ran across the following yum error after migrating a system from being a client of Satellite 5.6 to Satellite 6.1. First here is the error:
# yum update Loaded plugins: package_upload, priorities, rhnplugin, search-disabled-repos, security, subscription-manager There was an error communicating with RHN. RHN Satellite or RHN Classic support will be disabled. Error Message: Please run rhn_register as root on this client Error Class Code: 9 Error Class Info: Invalid System Credentials. Explanation: An error has occurred while processing your request. If this problem persists please enter a bug report at bugzilla.redhat.com. If you choose to submit the bug report, please be sure to include details of what you were trying to do when this error occurred and details on how to reproduce this problem. Setting up Update Process rhel-6-server-rpms | 2.0 kB 00:00 rhel-6-server-satellite-tools-6.1-rpms | 2.1 kB 00:00 No Packages marked for Update
sed -i -e 's/enabled=1/enabled=0/g' /etc/yum/pluginconf.d/rhnplugin.conf
sed -i -e 's/enabled\s*=\s*1/enabled=0/g' /etc/yum/pluginconf.d/rhnplugin.conf
More details can be found using the yum.conf man page.
Hope that is helpful.