Since the error message points to some problem with the Placement service, I would use commands to access Placement manually. If that works, I would then check whether the compute node is correctly configured to access Placement.

nova host-list ERROR (KeyError): 'version'

This indicates incompatible versions of Python libraries and/or the nova command line client.

Talking about placement, it happened that at verifying stage I saw some things, first, when I run "placement-status upgrade check" I must do it as root to get correct output (all other verifications are done with a sudo user) and placement-status upgrade check says that it is not a openstack command

I think that in Stein, Placement is still part of Nova, except if you explicitly configure it to be separate. In the former case, you would probably not have placement-status, but nova-status would give you some information about the health of Placement.

whats nova-compute.log says?

[None] Failed to retrieve resource provider tree from placement API for UUID blablabla ERROR nova.compute.manager KeyError: 'allocations' This is what I found mostly useful on compute node logs