gistfile1.txt

diff --git a/nova/objects/instance.py b/nova/objects/instance.py
index 27fd416..0df32ab 100644
--- a/nova/objects/instance.py
+++ b/nova/objects/instance.py
@@ -324,17 +324,32 @@ 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 heal those here so callers don't explode trying
+        # to load instance.flavor.disabled.
+        def _heal_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'])
+        _heal_disabled(self.flavor)
         if flavor_info['old']:
             self.old_flavor = objects.Flavor.obj_from_primitive(
                 flavor_info['old'])
+            _heal_disabled(self.old_flavor)
         else:
             self.old_flavor = None
         if flavor_info['new']:
             self.new_flavor = objects.Flavor.obj_from_primitive(
                 flavor_info['new'])
+            _heal_disabled(self.new_flavor)
         else:
             self.new_flavor = None
         self.obj_reset_changes(['flavor', 'old_flavor', 'new_flavor'])