So in my typical fashion, I attempted to strip out every bit of software I knew I wouldn't use.
Part of that was the Zorin Tour and Gnome Tour. Since they're unremovable in the application System Tools > Software, I searched for and removed the files.
That has a side effect. When updating or installing files, I get:
dpkg: warning: files list file for package 'zorin-gnome-tour-autostart' missing; assuming package has no files currently installed
dpkg: warning: files list file for package 'zorin-os-tour-video' missing; assuming package has no files currently installed
dpkg: warning: files list file for package 'gnome-tour' missing; assuming package has no files currently installed
No problem... in Terminal: sudo gedit /var/lib/dpkg/status
Search for 'tour' and remove the references to 'zorin-gnome-tour-autostart', 'zorin-os-tour-video' and 'gnome-tour'. Then save the file.
This error can also occur if an installation or deinstallation went wrong.