I found out that it is not enough to disable userdefined modules. They have to be totally deleted 🙁 So you might have to update your upgrade instruction with that part.
So next step is to figure out why my language file does not work – I will close this and make a new tread for help with this 🙂
Regards, Jamie Jaconelli
admin and owner of a user customized version of kiwitrees (contain 3 family trees)