So I was trying to root my Xperia Z2, starting by unlocking the bootloader. I rushed through the confirmation boxes to get the code, I entered it on fastboot... And realized I haven't made a backup. Phone restored to factory state. At least I had saved my photos on the SD card, but all the files, settings, configs and apps were gone along with my IM conversation database that I hadn't backed up for a month.

And I still haven't finished rooting that device.

When it comes to older Sony phones (I'm writing this from my Z3 right now), you should always use a locked BL tool for just a quick root (personally I install XZDR and make a NANDroid, but if you can get Titanium to work then that's also good). One rule I have stuck to for the past 5 years though, is that before I buy a phone I check XDA for any existing ROMs, and look on the manufacturer's page to see if there are open source archives available. Only then will I decide to buy the phone. I cannot run anything that isn't at least AOSP based (because it just annoys the hell out of me), so this immediately removes 90% of the market's stock ROMs. The only phones I think I'd use with the stock ROM are Pixel and Nokia. Still, older phones are usually at the top of my list, and anything that bears a Samsung logo is second from the bottom, just above Apple. Also, most apps these days have Google cloud backup available should you have it enabled. Still sucks losing data though.