Arch has a reputation for breaking. In practice, almost every broken system I have been asked to look at broke for one of a handful of reasons, all avoidable.
1. Never partially upgrade
pacman -Sy package is the single most reliable way to destroy an install. It refreshes the database and installs one package against libraries that have not moved. There is exactly one correct upgrade command:
sudo pacman -Syu2. Read the news before a big one
Manual interventions are announced. A one-line check is enough to avoid the two that matter each year:
curl -s 'https://archlinux.org/feeds/news/' | grep -o '<title>[^<]*' | head -53. Handle pacnew files the same week
sudo pacdiff -sA .pacnew left for six months becomes a config divergence nobody can reconstruct. Deal with them while the change is still in your head.
4. Keep a cache, keep a snapshot
paccache -rk2 keeps two versions of every package, which is a downgrade path that does not need the network. Combined with a pre-transaction snapshot, recovery from a bad upgrade is a reboot rather than a reinstall.
5. Fewer AUR packages than you think you need
Every AUR package is a build script maintained by one person. They are the first thing to break after a major library bump. Audit the list quarterly and drop anything you have not run in that time.
6. Know how to chroot in
Practise it once while nothing is wrong: boot the USB, mount, arch-chroot /mnt, fix, exit, reboot. Ten minutes of rehearsal turns an unbootable machine from a crisis into a chore.