After reluctantly deleting a bunch of apps that I actually use- I kept getting this message when trying to update.
I found this page, turned off Time Machine, and tried again. 15 minutes left on the update but it seems to be going well now.
Totalnoob
Users receive reputation points by contributing quality content to the forums.
Posts include post and replies published on the forums.
Post authors can mark replies as Accepted to indicate successful solutions.
Apple Developer Forums admins can mark replies as Apple Recommended to indicate an approved solution