I'm still on 14.04 and I'm using my laptop for things related to a production server. I need a way to have an absolutely rock solid backup plan before my upgrade to next LTS. I'm sure nobody wants to spend 8 hours sorting out dependencies, but before I pull the trigger, I need to know that I can easily roll the changes back.
How can I roll back to a previous image if I get weird errors after the upgrade?
Clone your system (root) partition to external media using Clonezilla.