After my recent woes with iOS updates (and a completely trivial Mojave update), but always saved by backups (I eventually found my iTunes backup password in my old journal, and put it in 1Password), I sympathize, but also laugh in their direction:
NEVER let a system auto-update. ALWAYS have backups.
Anyone who lets their OS or software update without backing up first, is asking to have their files deleted. Anyone who doesn't maintain a couple backups, with at least one offsite, is asking to have their files deleted. I often say people don't learn about backups until after their first catastrophic data loss, and sometimes not then, but you can beat the curve and learn first.
I use a daily cloud backup, and a weekly to monthly full-disk backup with SuperDuper!. Many people like Time Machine, it doesn't fit my workflow well, but it's a good tool for non-technical users.
- Mac Power Users #318 Backing Up: David's "Three-Two-One" rule, and Katie's Four Laws of Backups.
You may be thinking, "I don't use a Mac!", but the advice is the same for other (lesser) computers, and you need it more. Only the specific apps for backup will differ. I'm looking for recommendations.