What happens if Ubuntu support ends?

Question

linux

I am using Ubutnu Xenial Xerus 16.04.6 LTS. The site says that the end of the support period is April 2021.
I know it won't be soon, but I just wanted to know what will happen if the deadline runs out?
Will it also be possible to fully use the OS?
Or is it possible to somehow upgrade to a new version without losing data?
What is the difference between supported and unsupported OS?

Answer 1

Good morning.
Can.
Install the new version clean, but do not format the "home" partition.
Data and some program settings will be saved. You will only need to install these programs again.

Answer 2

I boot into live, mount the disk, everything is in /, I create any folder in the root, usually _, then mv * _. Then I install the new version without formatting, when I boot up, I just transfer / copy the config files I'm interested in to the new OS from _. If something went wrong, then you can very easily switch to the old OS.

Answer 3

I partition the disk into three partitions: a swap, an active Ubuntu-16.04.7 system, and something newer in a minimal installation (let's say 20.04.1). From the same inactive system, you can boot and check the active one. And transfer the data gradually from day to day ... Then set newer, etc. Well, about once a year or two...