diff --git a/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/030_require_cell_setup.py b/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/030_require_cell_setup.py
index fe3822e19c02..e59b12433abf 100644
--- a/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/030_require_cell_setup.py
+++ b/nova/db/sqlalchemy/api_migrations/migrate_repo/versions/030_require_cell_setup.py
@@ -10,12 +10,15 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from oslo_log import log as logging
 from sqlalchemy import MetaData, Table, func, select
 
 from nova import exception
-from nova.i18n import _
+from nova.i18n import _, _LW
 from nova import objects
 
+LOG = logging.getLogger(__name__)
+
 
 def upgrade(migrate_engine):
     meta = MetaData()
@@ -51,7 +54,7 @@ def upgrade(migrate_engine):
     host_mappings = Table('host_mappings', meta, autoload=True)
     count = select([func.count()]).select_from(host_mappings).scalar()
     if count == 0:
-        msg = _('No host mappings were found, but are required for Ocata. '
-                'Please run nova-manage cell_v2 simple_cell_setup before '
-                'continuing.')
-        raise exception.ValidationError(detail=msg)
+        msg = _LW('No host mappings were found, but are required for Ocata. '
+                  'Please run nova-manage cell_v2 simple_cell_setup before '
+                  'continuing.')
+        LOG.warning(msg)
diff --git a/nova/tests/unit/db/test_sqlalchemy_migration.py b/nova/tests/unit/db/test_sqlalchemy_migration.py
index 442c9f115030..46fa133f9dad 100644
--- a/nova/tests/unit/db/test_sqlalchemy_migration.py
+++ b/nova/tests/unit/db/test_sqlalchemy_migration.py
@@ -437,9 +437,9 @@ class TestNewtonCellsCheck(test.NoDBTestCase):
                                     database_connection='fake')
         cell1.create()
 
-        self.assertRaisesRegex(exception.ValidationError,
-                               'host mappings',
-                               self.migration.upgrade, self.engine)
+        with mock.patch.object(self.migration, 'LOG') as log:
+            self.migration.upgrade(self.engine)
+            self.assertTrue(log.warning.called)
 
     def test_upgrade_with_required_mappings(self):
         self._flavor_me()