diff --git a/ironic/conductor/base_manager.py b/ironic/conductor/base_manager.py
index 52bf434a20..b472b78fbb 100644
--- a/ironic/conductor/base_manager.py
+++ b/ironic/conductor/base_manager.py
@@ -171,7 +171,8 @@ class BaseConductorManager(object):
             self._register_and_validate_hardware_interfaces(hardware_types)
         except (exception.DriverLoadError, exception.DriverNotFound,
                 exception.ConductorHardwareInterfacesAlreadyRegistered,
-                exception.InterfaceNotFoundInEntrypoint) as e:
+                exception.InterfaceNotFoundInEntrypoint,
+                exception.NoValidDefaultForInterface) as e:
             with excutils.save_and_reraise_exception():
                 LOG.error(_LE('Failed to register hardware types. %s'), e)
                 self.del_host()
@@ -263,6 +264,8 @@ class BaseConductorManager(object):
                                hardware type object.
         :raises: ConductorHardwareInterfacesAlreadyRegistered
         :raises: InterfaceNotFoundInEntrypoint
+        :raises: NoValidDefaultForInterface if the default value cannot be
+                 calculated and is not provided in the configuration
         """
         # first unregister, in case we have cruft laying around
         self.conductor.unregister_all_hardware_interfaces()
@@ -272,6 +275,9 @@ class BaseConductorManager(object):
             for interface_type, interface_names in interface_map.items():
                 default_interface = driver_factory.default_interface(
                     ht, interface_type)
+                if default_interface is None:
+                    raise exception.NoValidDefaultForInterface(
+                        interface_type=interface_type, node=None, driver=ht)
                 self.conductor.register_hardware_interfaces(ht_name,
                                                             interface_type,
                                                             interface_names,
diff --git a/ironic/tests/unit/conductor/test_base_manager.py b/ironic/tests/unit/conductor/test_base_manager.py
index 74ebfe8891..aff8c8f9d3 100644
--- a/ironic/tests/unit/conductor/test_base_manager.py
+++ b/ironic/tests/unit/conductor/test_base_manager.py
@@ -338,6 +338,31 @@ class RegisterInterfacesTestCase(mgr_utils.ServiceSetUpMixin,
         # we're iterating over dicts, don't worry about order
         reg_mock.assert_has_calls(expected_calls)
 
+    def test__register_and_validate_no_valid_default(self,
+                                                     esi_mock,
+                                                     default_mock,
+                                                     reg_mock,
+                                                     unreg_mock):
+        # these must be same order as esi_mock side effect
+        hardware_types = collections.OrderedDict((
+            ('fake-hardware', fake_hardware.FakeHardware()),
+        ))
+        esi_mock.side_effect = [
+            collections.OrderedDict((
+                ('management', ['fake', 'noop']),
+                ('deploy', ['agent', 'iscsi']),
+            )),
+        ]
+        default_mock.return_value = None
+
+        self.assertRaises(
+            exception.NoValidDefaultForInterface,
+            self.service._register_and_validate_hardware_interfaces,
+            hardware_types)
+
+        unreg_mock.assert_called_once_with(mock.ANY)
+        self.assertFalse(reg_mock.called)
+
 
 class StartConsolesTestCase(mgr_utils.ServiceSetUpMixin,
                             tests_db_base.DbTestCase):
diff --git a/ironic/tests/unit/conductor/test_manager.py b/ironic/tests/unit/conductor/test_manager.py
index 7998721504..4b2b45e1ac 100644
--- a/ironic/tests/unit/conductor/test_manager.py
+++ b/ironic/tests/unit/conductor/test_manager.py
@@ -637,7 +637,6 @@ class VendorPassthruTestCase(mgr_utils.ServiceSetUpMixin,
         self._test_vendor_passthru_async('fake', None)
 
     def test_vendor_passthru_async_hw_type(self):
-        self.config(enabled_vendor_interfaces=['fake'])
         self._test_vendor_passthru_async('fake-hardware', 'fake')
 
     @mock.patch.object(task_manager.TaskManager, 'upgrade_lock')
@@ -3845,12 +3844,10 @@ class RaidHardwareTypeTestCases(RaidTestCases):
     raid_interface = 'fake'
 
     def test_get_raid_logical_disk_properties_iface_not_supported(self):
-        self.config(enabled_raid_interfaces=[])
-        self._start_service()
-        exc = self.assertRaises(messaging.rpc.ExpectedException,
-                                self.service.get_raid_logical_disk_properties,
-                                self.context, self.driver_name)
-        self.assertEqual(exception.UnsupportedDriverExtension, exc.exc_info[0])
+        # NOTE(jroll) we don't run this test as get_logical_disk_properties
+        # is supported on all RAID implementations, and we cannot have a
+        # null interface for a hardware type
+        pass
 
     def test_set_target_raid_config_iface_not_supported(self):
         # NOTE(jroll): it's impossible for a dynamic driver to have a null
@@ -4624,7 +4621,8 @@ class ManagerCheckDeployTimeoutsTestCase(mgr_utils.CommonMixIn,
 
 
 @mgr_utils.mock_record_keepalive
-class ManagerTestProperties(tests_db_base.DbTestCase):
+class ManagerTestProperties(mgr_utils.ServiceSetUpMixin,
+                            tests_db_base.DbTestCase):
 
     def setUp(self):
         super(ManagerTestProperties, self).setUp()
@@ -4633,7 +4631,7 @@ class ManagerTestProperties(tests_db_base.DbTestCase):
     def _check_driver_properties(self, driver, expected):
         mgr_utils.mock_the_extension_manager(driver=driver)
         self.driver = driver_factory.get_driver(driver)
-        self.service.init_host()
+        self._start_service()
         properties = self.service.get_driver_properties(self.context, driver)
         self.assertEqual(sorted(expected), sorted(properties.keys()))
 
@@ -4753,16 +4751,13 @@ class ManagerTestProperties(tests_db_base.DbTestCase):
 
 
 @mgr_utils.mock_record_keepalive
-class ManagerTestHardwareTypeProperties(tests_db_base.DbTestCase):
-
-    def setUp(self):
-        super(ManagerTestHardwareTypeProperties, self).setUp()
-        self.service = manager.ConductorManager('test-host', 'test-topic')
+class ManagerTestHardwareTypeProperties(mgr_utils.ServiceSetUpMixin,
+                                        tests_db_base.DbTestCase):
 
     def _check_hardware_type_properties(self, hardware_type, expected):
         self.config(enabled_hardware_types=[hardware_type])
         self.hardware_type = driver_factory.get_hardware_type(hardware_type)
-        self.service.init_host()
+        self._start_service()
         properties = self.service.get_driver_properties(self.context,
                                                         hardware_type)
         self.assertEqual(sorted(expected), sorted(properties.keys()))
diff --git a/releasenotes/notes/conductor-startup-invalid-defaults-b7bd0589a3bf474b.yaml b/releasenotes/notes/conductor-startup-invalid-defaults-b7bd0589a3bf474b.yaml
new file mode 100644
index 0000000000..195b90fbdd
--- /dev/null
+++ b/releasenotes/notes/conductor-startup-invalid-defaults-b7bd0589a3bf474b.yaml
@@ -0,0 +1,5 @@
+---
+upgrade:
+  - The conductor will now fail to start up if invalid configuration is
+    provided, such that a default interface implementation for any enabled
+    hardware type cannot be found.