[Zope] File objects AttributeError:alt

I've recently upgraded my Zope version from 2.7.6 to 2.9.8. I've recently discovered that older File objects are generating an AttributeError: alt whenever I call manage_changeProperties() on those File object instances. I'm aware of the change to lib/python/OFS/Image.py that removed the alt class attr from the File class. I thought my File objects would have automatically updated too but, apparently not. I just tried doing the following: objs = context.ZopeFind(context.this(), obj_metatypes=['File'], search_sub=1) for k,v in objs: if hasattr('alt',v): delattr('alt',v) The above code didn't seem to do anything to fix the issue. Any suggestions would be greatly appreciated. Sincerely, Tom Palermo