Preliminary Precautions

Before performing any system-level update, you should always back up all your important data. This ensures you’ll have something to restore if you encounter any problems during the update. If you’re here because your Mac has already frozen (which I’m willing to bet most of you are), don’t worry. Chances are your data will remain intact. Just remember to backup your data in the future! Also, don’t update macOS if your hard drive is running out of space; I’d recommend keeping at least 30GB free. Now onto the solutions to fix your frozen Mac.

1. Disable FileVault

FileVault is a security feature that can help prevent unauthorized access to the data on your Mac’s startup disk. However, it can occasionally interfere with your macOS updates, as it may enter a loop where it tries to apply encryption to your updated OS. When updating macOS, it may help to disable FileVault:

  1. Select the Apple logo in your Mac’s menu bar.
  2. Navigate to “System Preferences … -> Security & Privacy -> FileVault.”
  3. You can now select “Turn Off FileVault … “ Now you should be able to update macOS without any issues. If you want the security benefits of full-disk encryption, you can reactivate FileVault after the update is complete.

2. Boot into Safe Mode

If macOS stalls mid-update, it’s possible a corrupted component or third-party application may be blocking the update. Safe Mode is a way to start up your Mac with the minimum number of components required for it to run. By stripping macOS down to its essentials, you may remove the obstacles that are interfering with the update. To boot into Safe Mode, power down your Mac as normal. You can then boot your Mac while holding the Shift key. After a few moments, macOS should boot into Safe Mode. From here you can perform the macOS update as normal – hopefully it goes off without a hitch!

3. Check the Apple System Status Page

If you’re struggling to download the macOS installer, there’s a chance that Apple’s servers could be to blame. Whenever Apple releases a new version of macOS, they typically receive an influx of people eager to download the update. This can put Apple’s servers under pressure. You can check the status of Apple’s various services at the official System Status page. If you’re struggling to update macOS, then scroll to the “macOS Software Update” section. If the accompanying icon is green, this indicates there’s no issue with Apple’s servers, and your problem lies elsewhere. If the icon is red or yellow, it’s good news: you’ve located the source of the problem! The bad news: there’s not much you can do until Apple’s servers are back to normal.

4. Wait It Out

The truth is that macOS updates take time, particularly if you’re using a slower Internet connection. Just because the progress bar hasn’t moved recently doesn’t automatically mean it’s never going to move again. Some macOS users have reported their updates taking upwards of ten hours. You can check whether macOS is still updating by pressing Command + L. If your Mac is still running correctly, an estimated install time should appear onscreen. As painful as it sounds, we’d always recommend leaving your Mac to sit for a few hours (having made sure it is connected to a power source), just to verify that it really is frozen. You can take this as an opportunity to grab a coffee, do some other work, run some errands, and generally catch up on life away from your Mac. Hopefully, you’ll return a few hours later to discover that macOS has updated successfully, and your Mac is now ready to use.

5. Refresh the Update

If you’re positive that macOS has frozen, you may get positive results following a refresh:

  1. Hold down you Mac’s power button and wait for about 30 seconds.
  2. Once macOS has powered down, press and hold the power button. The update should now resume.
  3. Press Command + L to check whether macOS is still installing. Your Mac should display an estimated install time. If this doesn’t help, it’s time to take more drastic measures.

6. Reset Your NVRAM

Your Mac’s Non-Volatile Random-Access Memory (NVRAM) is a small amount of memory that’s dedicated to storing settings that macOS needs to access quickly. This includes speaker volume, screen resolution, and kernel panic information. If you’re struggling to update macOS, you may get positive results by wiping the kernel panic information, so let’s try resetting the NVRAM:

  1. Shut down your computer as normal. Wait a few moments to ensure the hard disks and fans have stopped spinning.
  2. Locate the Command + Option + P + R keys, as you’ll be using these keys in a moment.
  3. Power up your Mac. Immediately after you hear the startup sound, press and hold the Command + Option + P + R keys.
  4. Continue holding these keys until you hear the startup chime for the second time.
  5. Release the keys. The NVRAM should have now reset, and hopefully you can install your update without any further issues.

7. Boot into Recovery Mode

If the update still won’t complete, it may help to start over by downloading a fresh copy of macOS. This requires you to boot into macOS’s Recovery Mode:

  1. Turn off your Mac as normal.
  2. Power up your Mac, but immediately press and hold the Command + R keys. Your Mac will now enter Recovery Mode.
  3. Once in Recovery Mode, click the Wi-Fi symbol in the upper-right corner, and make sure you’re connected to a fast, reliable network.
  4. In the popup that appears, select “Reinstall macOS.” You can now follow the onscreen instructions to download and install a fresh copy of macOS.

1. What if I get the message that “an error occurred while downloading the selected updates”?

If you get the above message, the good news is that at least your Mac hasn’t frozen mid-update! Many of the same fixes we’ve listed here apply to the above error too, but another thing you should try is checking that the date and time on your Mac are correct. To do this, press CMD + Space, search for “Date & Time”, then check the “Set date and time automatically” box and try downloading the update again.

2. Is there another way to install Mac updates?

If you’re finding that your macOS updates keep freezing or not installing properly through your Mac and Apple’s servers, it’s always good to have a bootable USB installer handy so that you can install the latest Mac version (and its updates) through that. You can learn how to create your own Mac USB installer here.

3. ‘Will I lose data if my macOS update has frozen?

No, usually Mac has fail-safe which mean that if your update freezes mid-update and you have to reboot, it will fall back to the last version of macOS you installed. The updates can freeze as much as they like, and you can keep hard-powering down your PC, and your data should still be intact.

What Next?

After you have fixed your frozen Mac and successfully updated to the latest macOS, you will want to learn how to customize Big Sur and make it your own or enable/disable the turbo boost for a better performance.