Upgrading section does mention: The best solution, whenever possible, is to backup your data and reinstall from scratch I've done remote upgrades of O

Upgrading section does mention: The best solution, whenever possible, is to backup your data and reinstall from scratch I've done remote upgrades of OpenBSD for almost every release over the past 18 years. The exceptions were the handful of times I migrated hardware or co-location facilities, taking the opportunity to install from scratch. Though more recently I've been running several machines so I've probably remotely upgraded at least one installation of every OpenBSD release since circa 2012. I've never had a problem. The risky part is aging hardware that may not survive the power spikes or internal initialization on reboot. Full disclosure: except for a few years in the 2000s where I ran Alpha and Sparc64, those were all i386 or amd64 architectures.