Comment 2 for bug 1490361

I've run into this yesterday, right after nova-compute upgrade to 2015.1.1 on all compute nodes in my environment. Turned out that openstack-nova 2015.1.0 (scheduler or perhaps one of its dependencies?) on controller is not something that nova-compute 2015.1.1 on compute nodes can live with!
Upgrading openstack-nova* and all of its dependencies on a controller to 2015.1.1 fixed the thing.