Upgrading Crostini Linux from Bullseye to Bookworm
ChromeOS Stable 121 rolled out to my ASUS Chromebox 3 and brought with it a one-click option to upgrade Crostini.
Crostini, the Debian based Linux container of chromeOS, was running Bullseye prior to that. ChromeOS 121 popped up a notification with a button offering to upgrade to Debian Bookworm 12.4. After backing up the container I clicked the button in the notification, skipped the backup option as I had already done it, and clicked another button to start the upgrade.
The process was uneventful. ChromeOS displayed a dialog with status messages informing on the progress, then a final message confirming the successful completion.
I checked out the main Linux programs I use and they all seem to be working fine on Bookworm, as well as everighing else. Some programs actually look better as they're built on GUI frameworks that come with an updated and refreshed design.
Upgrading Crostini from Buster to Bullseye a couple of yeas earlier was less smooth. Back then chromeOS didn't provide any user interface for activating the upgrade, so I had to manually run a script. Although the process completed with a few errors, Bullseye has always worked fine on Crostini since then.