An upgrade to macOS 27 Golden Gate usually takes under an hour. When it doesn't, it tends to stall at the same few points: a download that won't finish, "Preparing macOS Golden Gate" that never ends, a progress bar frozen at "About a minute remaining," or a restart that lands you back on your old macOS.

Most of these are recoverable without losing anything. The key is knowing which stage you're in, and when it's safe to interrupt.

Before anything else: if the Mac is in the middle of installing and showing an Apple logo with a progress bar, don't force it off unless it has been stuck for several hours with no disk or fan activity. Interrupting at the wrong moment, especially during a firmware update, is the one thing that can turn a slow install into a real problem.

How the upgrade works

It helps to know what each stage is doing:

  1. Downloading. Software Update fetches the upgrade package.
  2. Preparing. The installer unpacks and verifies the package and stages the new system alongside your current one. This is disk-heavy and can take a long time on a nearly full drive.
  3. Restart and install. The Mac restarts, installs the new sealed system volume, updates firmware on Apple silicon, and migrates settings. The screen may go dark or restart more than once.
  4. First login and background setup. Golden Gate starts indexing and downloading Apple Intelligence components. This isn't part of the install, but it makes the first hours slow.

Stuck downloading or "Checking for updates"

Likely causes: Apple's servers are overloaded in release week, a VPN or DNS filter is blocking Apple's update servers, or the Mac is enrolled in beta updates.

Fixes:

  • Check Apple's System Status page for "macOS Software Update."
  • Disconnect from VPNs and pause ad blocking or DNS filtering.
  • Make sure Beta Updates is off in System Settings > General > Software Update.
  • Run softwareupdate --list in Terminal to see an actual error message.
  • If it keeps failing, download the full installer instead: softwareupdate --fetch-full-installer --full-installer-version 27.0.

If a partial download seems stuck, restart the Mac before trying again. Software Update usually discards incomplete downloads on its own.

Stuck on "Preparing macOS Golden Gate"

How long is normal: anywhere from 10 minutes to over an hour, depending on your Mac and how full the drive is. A remaining-time estimate that doesn't change for a long while isn't necessarily frozen.

How to tell if it's working: open Activity Monitor and look at the Disk tab. Sustained write activity from update-related processes means it's progressing. You can also watch the installer's logs: 

log stream --predicate 'process == "softwareupdated"' --style compact

If it's truly stuck (no disk activity and no new log lines for 30 minutes or more):

  1. Check free space with df -h /System/Volumes/Data. You want about 40 GB available. Low space is the most common reason Preparing stalls.
  2. Cancel the update if the option is available, restart, free up space, and try again.
  3. Try starting the upgrade from Safe Mode, which prevents third-party login items and extensions from interfering. On Apple silicon: shut down, press and hold the power button until startup options appear, select your startup disk, hold Shift, and click Continue in Safe Mode.

Stuck on "About a minute remaining" or "Verifying"

Both stages are known for looking frozen. Verification checks the integrity of a large package, and the final-minute stage often involves work the progress bar doesn't reflect.

What to do: stay connected to the internet and wait. These stages commonly take 20 to 40 minutes on their own, sometimes longer. Some stalls happen because the network dropped briefly; reconnecting usually lets it continue.

Only intervene if there's been no change, no disk activity, and no new log output for well over an hour.

Stuck during the install itself (Apple logo and progress bar)

How long is normal: 20 to 60 minutes, sometimes more on older Macs. The Mac may restart and the screen may go black between phases.

Don't interrupt as long as the progress bar moves occasionally or the Mac restarts on its own.

If it has been stuck for several hours:

  1. Press and hold the power button until the Mac turns off.
  2. Wait 30 seconds, then turn it on.
  3. In many cases the installer resumes or rolls back to your previous macOS.

The Mac restarted into your old macOS

Sometimes the upgrade appears to complete, but you log in and you're still on Tahoe or Sequoia. The installer hit a problem and safely rolled back. Your data is fine.

Common reasons:

  • Not enough free space during the final stage.
  • A third-party kernel or system extension that isn't compatible, such as security, VPN, or driver software.
  • A failure to verify with Apple's servers during installation.

What to do:

  1. Free up space to about 40 GB or more.
  2. Update or temporarily uninstall security software, VPN clients, and drivers.
  3. Retry from Safe Mode.
  4. If you see "Failed to personalize the software update," check your internet connection and Date & Time settings, then try again later. This step requires contacting Apple's servers.

Last resort: reinstall from macOS Recovery

If the Mac won't start normally after a failed upgrade, macOS Recovery can reinstall macOS without erasing your data, as long as you choose Reinstall and don't erase the disk first.

  1. Shut down. Press and hold the power button until "Loading startup options" appears.
  2. Click Options, then Continue.
  3. Choose Reinstall macOS and follow the prompts. Don't use Disk Utility to erase anything.

Recovery installs the most recent macOS your Mac supports, or the version it can reach. Your files and apps stay in place.

If the Mac won't reach Recovery at all, that's the rare case for a DFU restore with another Mac, which Apple or an authorized service provider can help with.

Prevent it next time

  • Keep at least 40 GB free before any major upgrade.
  • Update security software, VPNs, and drivers before upgrading.
  • Make a backup you've tested.
  • Start the upgrade when you won't need the Mac for a couple of hours, plugged in and on a stable connection.
  • Don't upgrade during the first hours after a release, when Apple's servers are busiest.

The short version

  • Downloading stalls: check server status, VPNs, and beta settings; use the full installer if needed.
  • Preparing stalls: almost always free space; check disk activity before assuming it's frozen.
  • "About a minute remaining" and "Verifying" often take 20 to 40 minutes. Wait.
  • Rolled back to your old macOS: free space, update extensions, retry in Safe Mode.
  • Won't boot: Recovery > Reinstall macOS keeps your data.