Second, update the modules one package at a time, fixing errors as you go, or else revert (or park the branch temporarily) if you find something you cannot fix easily. That way you don’t break anything and you can always instantly step back to before the update.
“Use source control or you will be really sad sooner or later.” - StarManta on the Unity3D forum boards
Please consider using proper industrial-grade source control in order to guard and protect your hard-earned work.
Personally I use git (completely outside of Unity) because it is free and there are tons of tutorials out there to help you set it up as well as free places to host your repo (BitBucket, Github, Gitlab, etc.).
As far as configuring Unity to play nice with git, keep this in mind:
Here’s how I use git in one of my games, Jetpack Kurt:
Using fine-grained source control as you work to refine your engineering:
Share/Sharing source code between projects:
Setting up an appropriate .gitignore file for Unity3D:
Generally setting Unity up (includes above .gitignore concepts):
It is only simple economics that you must expend as much effort into backing it up as you feel the work is worth in the first place.