!! Upgrading a system can take several hours, depending on the number of installed packages and the speed of the system, especially its hard disks. While the download portion of the upgrade can be done separately, the actual install portion should be done in a single pass. Most of the upgrade process is quite hands-off, but some administrator action is needed towards the end of the process if the system has a custom configuration. !!
First, ensure your system is up-to-date in it’s current release.
sudo apt-get update
sudo apt-get upgrade
sudo apt-get full-upgrade
If you haven’t already, ensure all backups are up-to-date.
In a text editor, replace the codename of your release with that of the next release in APT’s package sources For instance, the line
deb https://deb.debian.org/debian/ buster main
should be replaced with
deb https://deb.debian.org/debian/ bullseye main
sudo nano /etc/apt/sources.list /etc/apt/sources.list.d/*
If you are migrating to Bookworm or later, then a new repo for non-free firmware is available. If you wish, you can add non-free and non-free-firmware, depending on your specific needs. For instance, the line deb https://deb.debian.org/debian/ bookworm main contrib non-free non-free-firmware or deb https://deb.debian.org/debian/ stable main contrib non-free non-free-firmware
Clean and update package lists
sudo apt-get clean
sudo apt-get update
Perform the major release upgrade, removing packages if required !! Interrupting this step after downloading has completed is an excellent way to stress-test your backups !!
sudo apt-get upgrade
sudo apt-get full-upgrade
Remove packages that are not required anymore !! Be sure to review this list: you may want to keep some of them !!
sudo apt-get autoremove
Reboot to make changes effective (optional, but recommended)
sudo shutdown -r now
Now check the output of uname -a ; lsb_release -a and you should see info about the upgraded system.
Last modified: Fri Oct 13 12:53:14 2023