Upgrade Linux Mint 20.0 20.1 or 20.2 to Version 20.3 Una. I follow the instructions from the Linux Mint Blog and easily perform the upgrade on a virtual machine, it's the same for real hardware and much faster than a VM in my experience.
Took about 35 mins for the VM but on 3 of my hardware systems it takes 5-10 minutes for the actual upgrade once you've done a backup with Timeshift, updated other packages etc. Mate Desktop used here but Cinnamon and Xfce should be the same other than the location of screen saver settings etc.
Do at your own risk as usual, intended as a guide of what to expect only. Your system and results may vary.