There is a bug in the installation program of Red Hat Enterprise Linux 6, which results in one or more
invalid records added to the /etc/zipl.conf file if the kernel-kdump package was a part of the 
initial installation. If these invalid records persist, the system might not
be able to boot into Red Hat Enterprise Linux 7.

Review the zipl.conf file and remove the invalid
records manually. Otherwise, redhat-upgrade-tool will attempt to remove
them.
