Unable to retrieve instances after openstack upgrade from newton to pike

[KamalaVenkatesh]

Description:
After openstack upgrade from newton to pike release,
1. Not able to list instances created before upgrade(though instances seems to be running).
2. Not able spawn new instances after upgrade from newton to pike.

Observation:

1.Able to ping ang login into VMs which are created before upgrade.

Below is the snippet when propmpted the command:

**nova list**
ERROR (ClientException): Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.
<class 'oslo_db.exception.DBError'> (HTTP 500) (Request-ID: req-47b8e78a-13dd-4fe7-9495-c84bbf51eb1b)

**openstack server list**
Unexpected API Error. Please report this at http://bugs.launchpad.net/nova/ and attach the Nova API log if possible.
<class 'oslo_db.exception.DBError'> (HTTP 500) (Request-ID: req-e6c51993-05b4-445e-b10f-4de8a7938b7f)

Note: When tried with openstack-dashboard webui faces same issue. It throws an error "unable to retrieve instances".

Steps to reproduce:
1.Deploy openstack newton.
2.Spawn some VMs
3.Upgrade openstack from newton to pike
4.list the VMs using "nova list" command

Expected results:
1. Should be able to list VMs spawned before upgrade.
2. Should able to spawn new VMs

Obtained result:
1. Unable to retrieve the instances
2. Not able to spawn VMs

Description of the environment:
* 9 baremetal nodes:
  -1st node has MAAS Deployed.
  -MAAS will deploy OS on all other nodes
  -Using juju openstack is deployed
*Node roles
  -3 compute node
  -3 controller node
  -2 network node
* Details:
  - Newton on Ubuntu 14.04
  - Compute: KVM

[KamalaVenkatesh (kamala)]

workaround:
Found some error logs in nova-api-os-compute.log like database error.
Attached complete nova-api-os-compute.log

[Sylvain Bauza (sylvain-bauza)]

Something is wrong with your upgrade as it claims that the 'services' table disappeared.

Given it's a specific deployment concern, setting the bug as Invalid since it doesn't like like a nova upstream project issue.