For those contemplating upgrading from Linux Mint 18.3 and earlier to 19. There is a significant change to how Mint runs in ver 19. Further, not all video drivers are supported as of yet.
As always, take a snapshot / backup before the upgrade so you can revert if needed.
Also, check to see if 19 supports your driver before the upgrade attempt.
I have an embedded video card (AMD R7) that was not supported at the time of the attempt to upgrade. Learned the hard way.
That’s why I still recommend the 18.3 and am letting the dust settle on 19 and 19.1 for awhile.
And very good suggestion about making a backup right away. And also go and set up “Timeshift” right away so that it starts to take mirrors at regular intervals as you prefer. Time shift works just like the “restore” feature in windows.