It has been a long time since its release Linux Mint 20. Eventually the distribution development team published instructions for the update. The remarkable thing is that this time you can only upgrade the Mint 19,3 64-bit.
Users running the 32-bit distribution are not so lucky.
The reason for this change is obvious, since Linux Mint 20 is based on Ubuntu 20.04 LTS, both operating systems are only available in 64-bit versions. Linux Mint 19.3 is the latest version to support the 32-bit architecture and will be available until April 2023.
If you are satisfied with the current installation of Linux Mint 19.3 and do not need to upgrade to version 20, as you can safely use your current operating system for one or two years.
Otherwise, you should take a look at the detailed guide below
The steps include a number of recommendations, e.g. to create a system snapshot with the TimeShift application. It also requires the installation of a new package, mintupgrade.
The other steps are standard and will be familiar to friends of the distribution.