Just updated a user to SFv8 from 7. And whenever we go through the database backup part of the install, it gets to the end and throws that error. I’ve tried rebooting, reinstalling, clearing plist files, and no joy. I did see this error in the SFv7 forums as being a r/w issue on the font vault so I’ll be checking that tomorrow morning. The user does have local admin rights.
edit: just realized there is a new post in here for the same issue. Feel free to close if needed.