Nervous of updating from Studio 2017 to 2019 - help

I've just bought the new update for 2019 - but I'm nervous to download it and use it as I've read a lot of comments on forums alluding to weird things happening after updating or during updating. Is the process of updating generally a simple one, free of difficulties? 

Also what will happen to current files I'm working on and my existing TM and termbases etc? I'm scared they will disappear.