How to do major upgrade from Linux Mint version 20.3 to Linux Mint version 21.0 Vanessa

This web page explains how to do major upgrade from Linux Mint 20.3 to Linux Mint 21.0
It can take several hours

Open terminal and type the following commands to update your OS and install the mintupgrade
$ apt update
$ apt install mintupgrade

Open terminal and type the following commands to launch the mintupgrade
$ sudo mintupgrade

Pop up window “Upgrade Tool, Linux Mint 21 Vanessa”
Click the button: Let’s go!

Phase 1: Preparation
A series of tests will now be performed to prepare the computer for the upgrade
Click the button OK
Follow the instructions on the screen until it is done

Phase 2: Simulation and download
A few more tests will be run and package updates will be downloaded
Click the button OK
Follow the instructions on the screen until it is done

Phase 3: Upgrade
The packages will now be upgraded
Click the button OK
Follow the instructions on the screen until it is done

Phase 4: Successful
Smiley face
The upgrade was successful
Reboot the computer for all the changes to take effect
Close the window

Open terminal and type the following commands to remove the mintupgrade and reboot your computer
$ apt remove mintupgrade
$ sudo reboot