Debian 12 "bookworm" quietly crossed a line in June 2026: regular security support ended, and it now runs on LTS. Debian 13 "trixie" has meanwhile matured through five point releases, which makes this the right moment to do the in-place upgrade. This guide covers the full procedure for a remote production server: the pre-flight checklist (including the interface-renaming trap that can cut a remote box off mid-upgrade), the three-command upgrade itself, and the trixie-specific changes to check afterwards: /tmp on tmpfs, the sysctl move, and OpenSSH 10.