Update MAC os safely

Who this is for: anyone with a Mac they use for work.

The short answer

Install security updates and minor updates promptly. Wait on major version upgrades — the ones with a new name like Sequoia or Tahoe — until your critical software has confirmed support, usually one to three months after release. If your Mac is managed by us, leave both alone; they're scheduled.

Know which kind of update you're being offered

• Rapid Security Response (e.g. 15.6.1 (a)) — small, targeted security fixes. Install these right away.
• Minor update (15.6 → 15.7) — bug fixes and security patches within the same OS. Low risk. Install within a week or two.
• Major upgrade (15 → 26, or a new name in the banner) — a new operating system. This is the one that breaks things. Wait.

Before any major upgrade

1. Confirm your backup ran. Check Time Machine's last backup date, or that your files show as synced in OneDrive. An upgrade is the worst possible time to discover backups have been failing since March.
2. Check your critical software. Accounting packages, practice management, dental or medical systems, CAD, point-of-sale, and anything with a hardware dongle or scanner. Look for a support statement from the vendor naming your exact macOS version. "Should be fine" from a support rep is not that.
3. Check your peripherals. Printers, label printers, check scanners, and card readers need updated drivers. These lag the OS by months.
4. Have 40–60 GB free and be on power and a reliable network.
5. Pick your timing. Friday afternoon, not Monday morning. Budget an hour and a half.

Installing

Open System Settings → General → Software Update. Minor updates appear directly. Major upgrades appear under Upgrade Now or in an "Other updates are available" link. Leave the Mac alone while it runs; it will restart more than once and can appear frozen on a progress bar for long stretches.

Recommended settings for a work Mac

Under Software Update → Automatic Updates (the ⓘ button):

• Check for updates: on
• Download new updates when available: on
• Install macOS updates: off — you want to choose the moment
• Install Security Responses and system files: on

Why waiting on ".0" releases is not paranoia

The first release of a new macOS lands in September or October each year, and the fixes for its worst problems land in the .1 and .2 releases over the following weeks. Nothing about a business Mac benefits from being early. Meanwhile, staying two or three major versions behind is its own risk — Apple only ships full security patches for roughly the current version and the two before it. The right position is one version behind and moving forward deliberately.

If a Mac is managed

Managed Macs get updates on a schedule we set, and you may see a deferral notice telling you an update will install after a certain date. You can postpone it a few times; don't postpone indefinitely. If a deadline lands badly, tell us and we'll move it.