https://ask.openstack.org/en/question/28659/failure-login-to-dashboard-on...
This post was downgraded 12 hr ago. I did backport F21 packages
to F20, to keep Horizon alive, nothing else.
For details on the H -> I update process see:
http://openstack.redhat.com/Upgrading_RDO_To_Icehouse
thanks,
Pádraig.