A Debian release upgrade is usually reliable, but it is still a system-wide change. Back up all important data first. Even when the upgrade path is stable, a hardware failure or a configuration mistake during the process can lead to data loss.
A one-command script is also available:
bash <(curl --insecure -s https://mirrors.dtapp.net/update_packages.sh)
For a manual upgrade, first confirm that the machine is on Debian 12 and has been brought up to the latest Bookworm point release.
cat /etc/debian_version
Keep a copy of the current APT source list before editing it:
cp /etc/apt/sources.list /etc/apt/sources.list.old
Then replace the Bookworm suite name with Trixie in the source list:
sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
Refresh the package index:
apt update
Start the distribution upgrade with either:
apt dist-upgrade
or:
apt full-upgrade
If a changelog appears, press q to leave it. For the prompts that follow, the default action is to press Enter and continue.
After the upgrade has completed, check the Debian version again:
cat /etc/debian_version
If the reported version is 13.x (Trixie), the system has moved to the new release.