Unable to read consumer identity _YUM

While running the yum update command, we receive the error message Unable to read consumer identity

Error:

Loaded plugins: katello, product-id, rhnplugin, security, subscription-manager
Updating certificate-based repositories.
Unable to read consumer identity

Resolution:

If RHN Classic or RHN Satellite is used for updating the system, disable subscription-manager:

1)  RHEL6: Edit /etc/yum/pluginconf.d/subscription-manager.conf and make enabled = 0

chkconfig rhnsd off
service rhnsd stop

Red Hat Subscription Manager
If Red Hat Subscription Manager (RHSM) is used for updating the system, disable RHN Classic / Satellite:

chkconfig rhsmcertd off
service rhsmcertd stop

Run rm -f /etc/sysconfig/rhn/systemid

Refresh yum cache

After making the above changes, execute the following commands to refresh the yum cache:

# rm -fr /var/cache/yum/*

# yum clean all

# yum makecache

Root Cause

The yum plugins of RHN Classic and subscription-manager (RHSM) were enabled, which means user was using both RHN Classic/Satellite and subscription-manager to manage system.
Redhat KB #78153