When a Hypervisor is upgraded for Red Hat Enterprise Virtualization 3.1 compatibility the upgrade will initially be listed in the Administration Portal as unreachable or in maintenance mode. This will be the case even where the upgrade was successful. To resolve this issue use the Administration Portal to put the Hypervisor into maintenance mode (if necessary) and then activate it manually to resume normal operation.
This issue only exists when upgrading from Hypervisors that include vdsm-4.9 to Hypervisors that include vdsm-4.9.6. The issue will not occur on subsequent upgrades.