Steps to upgrade from Bookworm

Debian Trixie (Debian 13) has been out for a bit, but I had some hiccups upgrading my containers from Bookworm (Debian 12). I have daily backups of these containers, so reverting was a bit of a chore, but not impossible. Now I'm able to upgrade with some fallback caution (which I should have exercised to begin with).

These instructions are available at Debian Releases page, feel free to verify there. I'm putting them up here for my own convenience:

#Update everything to latest
apt update && apt upgrade && apt full-upgrade && apt --purge autoremove
reboot

#Verify that debian_version is 12.x (STOP IF NOT 12!)
cat /etc/debian_version

#Check for any pinned or held packages
apt list '?narrow(?installed, ?not(?origin(Debian)))'
apt-mark showhold

#Swap bookworm for trixie in repo files
sed -i 's/bookworm/trixie/g' /etc/apt/sources.list
sed -i 's/bookworm/trixie/g' /etc/apt/sources.list.d/*

#Carry out update
apt update
apt upgrade --without-new-pkgs -y
apt full-upgrade -y
reboot

#Verify that debian_version is 13.x
cat /etc/debian_version

#Modernize apt sources to v3
apt modernize-sources -y

#My update script, pretty much like first command
./aptrun.sh

Apt is upgraded to v3 in Trixie, which brings a lot of sorely-needed upgrades: proper multithreading, https transport improvements (these seem to improve speed of update checks), and big changes to source repo entries. Please check at the Debian upgrade page above, but these are essentially changing from URL/path format to include key information like URI, separate suite/component sections, and signing information.