sed -i 's/debian-security buster\/updates/ bullseye-security/g' /etc/apt/sources.list
sed -i 's/buster/bullseye/g' /etc/apt/sources.list
sed -i 's/buster/bullseye/g' /etc/apt/sources.list.d/pgdg.list
sed -i 's/debian 10/debian 11/g' /etc/apt/sources.list.d/zammad.list

apt clean; apt update
apt upgrade
apt dist-upgrade

# Current stable psql version is 16
pg_dropcluster --stop 16 main
pg_upgradecluster 11 main /var/lib/postgresql/16/

# Below two are old (pre recent psql CVE)
# pg_dropcluster --stop 13 main
# pg_upgradecluster 11 main /var/lib/postgresql/13/

apt autoremove
shutdown -r now