nova-compute second host error

2013-12-10 20:42:15.574 1491 INFO nova.openstack.common.periodic_task [-] Skipping periodic task _periodic_update_dns because its interval is negative
2013-12-10 20:42:15.626 1491 INFO nova.virt.driver [-] Loading compute driver 'xenapi.XenAPIDriver'
2013-12-10 20:42:15.990 1491 CRITICAL nova [-] 'XenAPISession' object has no attribute '_virtapi'
2013-12-10 20:42:15.990 1491 TRACE nova Traceback (most recent call last):
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/bin/nova-compute", line 10, in <module>
2013-12-10 20:42:15.990 1491 TRACE nova     sys.exit(main())
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/cmd/compute.py", line 68, in main
2013-12-10 20:42:15.990 1491 TRACE nova     db_allowed=False)
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 257, in create
2013-12-10 20:42:15.990 1491 TRACE nova     db_allowed=db_allowed)
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/service.py", line 139, in __init__
2013-12-10 20:42:15.990 1491 TRACE nova     self.manager = manager_class(host=self.host, *args, **kwargs)
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/compute/manager.py", line 450, in __init__
2013-12-10 20:42:15.990 1491 TRACE nova     self.driver = driver.load_compute_driver(self.virtapi, compute_driver)
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/virt/driver.py", line 1108, in load_compute_driver
2013-12-10 20:42:15.990 1491 TRACE nova     virtapi)
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/openstack/common/importutils.py", line 52, in import_object_ns
2013-12-10 20:42:15.990 1491 TRACE nova     return import_class(import_value)(*args, **kwargs)
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/virt/xenapi/driver.py", line 142, in __init__
2013-12-10 20:42:15.990 1491 TRACE nova     self._session = XenAPISession(url, username, password, self.virtapi)
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/virt/xenapi/driver.py", line 666, in __init__
2013-12-10 20:42:15.990 1491 TRACE nova     self.host_uuid = self._get_host_uuid()
2013-12-10 20:42:15.990 1491 TRACE nova   File "/usr/lib/python2.7/dist-packages/nova/virt/xenapi/driver.py", line 698, in _get_host_uuid
2013-12-10 20:42:15.990 1491 TRACE nova     aggr = self._virtapi.aggregate_get_by_host(
2013-12-10 20:42:15.990 1491 TRACE nova AttributeError: 'XenAPISession' object has no attribute '_virtapi'
2013-12-10 20:42:15.990 1491 TRACE nova