diff --git a/nova/objects/instance.py b/nova/objects/instance.py
index c0f0cd5062f8..1810c12a94d7 100644
--- a/nova/objects/instance.py
+++ b/nova/objects/instance.py
@@ -320,17 +320,32 @@ class Instance(base.NovaPersistentObject, base.NovaObject,
     def _flavor_from_db(self, db_flavor):
         """Load instance flavor information from instance_extra."""
 
+        # Before we stored flavors in instance_extra, certain fields, defined
+        # in nova.compute.flavors.system_metadata_flavor_props, were stored
+        # in the instance.system_metadata for the embedded instance.flavor.
+        # The "disabled" field wasn't one of those keys, however, so really
+        # old instances that had their embedded flavor converted to the
+        # serialized instance_extra form won't have the disabled attribute
+        # set and we need to default those here so callers don't explode trying
+        # to load instance.flavor.disabled.
+        def _default_disabled(flavor):
+            if 'disabled' not in flavor:
+                flavor.disabled = False
+
         flavor_info = jsonutils.loads(db_flavor)
 
         self.flavor = objects.Flavor.obj_from_primitive(flavor_info['cur'])
+        _default_disabled(self.flavor)
         if flavor_info['old']:
             self.old_flavor = objects.Flavor.obj_from_primitive(
                 flavor_info['old'])
+            _default_disabled(self.old_flavor)
         else:
             self.old_flavor = None
         if flavor_info['new']:
             self.new_flavor = objects.Flavor.obj_from_primitive(
                 flavor_info['new'])
+            _default_disabled(self.new_flavor)
         else:
             self.new_flavor = None
         self.obj_reset_changes(['flavor', 'old_flavor', 'new_flavor'])
diff --git a/nova/tests/unit/objects/test_instance.py b/nova/tests/unit/objects/test_instance.py
index cb7df80a93bd..3ea396694745 100644
--- a/nova/tests/unit/objects/test_instance.py
+++ b/nova/tests/unit/objects/test_instance.py
@@ -350,6 +350,23 @@ class _TestInstanceObject(object):
                                          inst.key_name,
                                          localonly=True)
 
+    @mock.patch.object(db, 'instance_get_by_uuid')
+    def test_lazy_load_flavor_from_extra(self, mock_get):
+        inst = objects.Instance(context=self.context, uuid=uuids.instance)
+        # These disabled values are only here for logic testing purposes to
+        # make sure we default the "new" flavor's disabled value to False on
+        # load from the database.
+        fake_flavor = jsonutils.dumps(
+            {'cur': objects.Flavor(disabled=False).obj_to_primitive(),
+             'old': objects.Flavor(disabled=True).obj_to_primitive(),
+             'new': objects.Flavor().obj_to_primitive()})
+        fake_inst = dict(self.fake_instance, extra={'flavor': fake_flavor})
+        mock_get.return_value = fake_inst
+        # Assert the disabled values on the flavors.
+        self.assertFalse(inst.flavor.disabled)
+        self.assertTrue(inst.old_flavor.disabled)
+        self.assertFalse(inst.new_flavor.disabled)
+
     @mock.patch.object(db, 'instance_get_by_uuid')
     def test_get_remote(self, mock_get):
         # isotime doesn't have microseconds and is always UTC