How to release upgrade your distribution

Upgrading from one stable release to the next (e.g. bullseye to bookworm) is done by following the release notes for your architecture. For most users, that means the Release Notes for AMD64.

Performing a release upgrade is not without risk. The upgrade may fail, leaving the system in a non-functioning state. USERS SHOULD BACKUP ALL DATA before attempting a release upgrade. DebianStability contains more information on these steps.

Upgrades are done with package management tools, root or sudo access, and generally involve the following steps.

Obtain a text shell.
- On desktop machines, switch to console tty via Ctrl+Alt+F3 (the upgrade should be done on a text console, because your desktop environment could freeze during post-install/service restarts, leaving the system in a broken state.)
Run the following:

# First, ensure your system is up-to-date in it's current release.
$ sudo apt update
$ sudo apt upgrade

# in a text editor, replace the codename of your release with the next release (eg. buster with bullseye) in APT 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/*

# clean and update package lists
$ sudo apt clean
$ sudo apt update

# perform major release upgrade, removing packages if required
$ sudo apt 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 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.

CategoryPackageManagement

DebianUpgrade

How to release upgrade your distribution