Unable to perform a live migration

Issue

• Live migration command shows that it completes, however the VM is never migrated to the new compute node:

(overcloud) [stack@undercloud ~]$ openstack server migrate --live overcloud-compute-0.localdomain 822517c5-b5ab-454e-a3be-7130522342c3 --wait
Complete

• The following is seen in /var/log/containers/nova/nova-compute.log:

2020-07-20 13:39:43.742 8 INFO oslo.privsep.daemon [req-fd2cea5b-a4c4-4cc3-8995-7b56d3154be0 6b3586b605b146a6b10d3e4c7faad1bc d64c3278801c40e3a4f71bcb046eacc5 - default default] Running privsep helper: ['sudo', 'nova-rootwrap', '/etc/nova
/rootwrap.conf', 'privsep-helper', '--config-file', '/usr/share/nova/nova-dist.conf', '--config-file', '/etc/nova/nova.conf', '--privsep_context', 'os_brick.privileged.default', '--privsep_sock_path', '/tmp/tmpChLU9K/privsep.sock']
2020-07-20 13:39:43.763 8 WARNING oslo.privsep.daemon [-] privsep log: sudo: unknown uid 42436: who are you?
2020-07-20 13:39:43.768 8 CRITICAL oslo.privsep.daemon [req-fd2cea5b-a4c4-4cc3-8995-7b56d3154be0 6b3586b605b146a6b10d3e4c7faad1bc d64c3278801c40e3a4f71bcb046eacc5 - default default] privsep helper command exited non-zero (1)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server [req-fd2cea5b-a4c4-4cc3-8995-7b56d3154be0 6b3586b605b146a6b10d3e4c7faad1bc d64c3278801c40e3a4f71bcb046eacc5 - default default] Exception during message handling: FailedToDropPrivileges: privsep helper command exited non-zero (1)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server Traceback (most recent call last):
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/server.py", line 166, in _process_incoming
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     res = self.dispatcher.dispatch(message)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 220, in dispatch
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     return self._do_dispatch(endpoint, method, ctxt, args)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_messaging/rpc/dispatcher.py", line 190, in _do_dispatch
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     result = func(ctxt, **new_args)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/nova/exception_wrapper.py", line 76, in wrapped
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     function_name, call_dict, binary)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     self.force_reraise()
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     six.reraise(self.type_, self.value, self.tb)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/nova/exception_wrapper.py", line 67, in wrapped
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     return f(self, context, *args, **kw)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/nova/compute/utils.py", line 1021, in decorated_function
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     return function(self, context, *args, **kwargs)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 215, in decorated_function
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     kwargs['instance'], e, sys.exc_info())
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 220, in __exit__
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     self.force_reraise()
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_utils/excutils.py", line 196, in force_reraise
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     six.reraise(self.type_, self.value, self.tb)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 203, in decorated_function
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     return function(self, context, *args, **kwargs)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/nova/compute/manager.py", line 6082, in pre_live_migration
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     connector = self.driver.get_volume_connector(instance)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/nova/virt/libvirt/driver.py", line 1214, in get_volume_connector
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     host=CONF.host)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/os_brick/utils.py", line 137, in trace_logging_wrapper
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     return f(*args, **kwargs)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/os_brick/initiator/connector.py", line 228, in get_connector_properties
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     execute=execute))
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/os_brick/initiator/connectors/iscsi.py", line 67, in get_connector_properties
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     initiator = iscsi.get_initiator()
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/os_brick/initiator/connectors/iscsi.py", line 957, in get_initiator
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     root_helper=self._root_helper)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/os_brick/executor.py", line 52, in _execute
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     result = self.__execute(*args, **kwargs)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/os_brick/privileged/rootwrap.py", line 169, in execute
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     return execute_root(*cmd, **kwargs)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_privsep/priv_context.py", line 206, in _wrap
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     self.start()
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_privsep/priv_context.py", line 217, in start
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     channel = daemon.RootwrapClientChannel(context=self)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server   File "/usr/lib/python2.7/site-packages/oslo_privsep/daemon.py", line 327, in __init__
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server     raise FailedToDropPrivileges(msg)
2020-07-20 13:39:43.863 8 ERROR oslo_messaging.rpc.server FailedToDropPrivileges: privsep helper command exited non-zero (1)