Comment 4 for bug 1317174

This workaround worked for me:

# on Controller host:
# remove icehouse-compat from nova.conf
openstack-config --del /etc/nova/nova.conf upgrade_levels compute

# restart nova services on Controller host
SVC_NOVA="openstack-nova-api openstack-nova-cert openstack-nova-scheduler openstack-nova-conductor openstack-nova-novncproxy openstack-nova-consoleauth"
for SVC in $SVC_NOVA; do service $SVC restart; done

Thats a workaround - yet not proper solution - as if upgrading Compute hosts one-by-one icehouse-compat has to be preserved until ALL hosts have been upgraded to icehouse - if Im getting this correct. So novnc consoles would be still out during the upgrade process for Computes running already on icehouse.