How to Fix: macOS Big Sur Fails to Boot

The newest version of macOS has been highly anticipated for some time. It was recently released and is already getting some good reviews from anyone who has successfully completed the installation.

However, there are also some issues being reported after installation that are frustrating if you are attempting the update.

macos big sur fails to boot

One of these issues is when macOS Big Sur fails to boot after you attempt an install. Let’s take a look at this problem and how to fix it here.

Why macOS Big Sur Can Fail to Boot?

There are often bugs, glitches, and other issues to iron out with any new update after it is released.

That’s why you see so many different versions of an update become available.

The initial release of Big Sur follows suit here, and some Mac users are reporting problems like this.

It could be due to an internal issue with your computer or other software installed on it, causing a conflict.

Fix #1: Reset NVRAM

If you have installed macOS Big Sur and your computer won’t restart, then you might need to reset the non-volatile RAM (NVRAM) on your machine.

NVRAM is a small dedicated amount of memory that your computer uses to store certain settings.

A new update can cause access to this memory to get a little out of whack, so a reset might be needed.

To perform an NVRAM reset on your Mac computer, follow these steps:

  1. Shut down your computer
  2. Wait for the computer to shut down completely and then press the power button.
  3. Immediately after the computer turns back on, press all of these keys at the same time: Option, Command, P, R.
    Hold these 4 keys down for about 20 seconds.
  4. If your computer plays a startup sound, wait until after hearing the sound a second time and then release the keys. If you have a Mac with a T2 security chip, wait for the Apple logo to appear and disappear twice and then release the keys.
  5. After this, your computer will restart, and your NVRAM parameters should be reset, allowing for macOS Big Sur to run properly.

Fix #2: Boot in Safe Mode

Another way to fix boot-up problems caused by macOS Big Sur is to boot up your computer in Safe Mode.

Safe Mode is a way to launch your computer without having any unnecessary software programs running.

This can help you figure out any specific conflicts with other software that might be causing your computer not to boot up after the Big Sur install.

If you can run Big Sur in safe mode, you will know that there is something else on your system causing the conflict.

You will then need to figure out what program is causing the issue, but at least you’ll know that the Big Sur install worked out ok.

To boot your computer in safe mode, follow these steps:

  1. Make sure that your computer is shut down completely.
  2. Press the power button to turn the computer back on.
  3. When you hear the startup sound, press the Shift key immediately.
  4. Release the shift key when you see the Login window.
  5. You are now in Safe Mode.
  6. If macOS Big Sur works in Safe Mode, you have a conflicting software program that needs to be addressed.

Note that this Safe Mode fix for when Big Sure fails to boot is commonly useful for anyone who has seen their computer go through a constant boot loop after attempting the update.

You can also reinstall macOS Big Sur from Safe Mode, which might fix the problem.

Fix #3: Force Restart Your Mac

If your Mac isn’t booting after installing Big Sur, the problem could be as easy as performing a force restart of the computer.

To force a restart, all you have to do is hold down the power button on your computer until it shuts down.

After that, wait for about ten seconds and then attempt to turn the computer back on.

Fix #4: Make Sure You are Connected to the Power Supply

This fix seems pretty straightforward, and that’s because it is.

If you don’t have your computer plugged into the power supply, you might experience some issues trying to boot it up after installing Big Sur.

Just make sure you have your computer plugged into the power supply and that it is indeed receiving power.

Fix #5: Run First Aid in Recovery Mode

Another option to explore is to run first aid from Disk Utility by restarting your Mac in recovery mode.

This can help repair any issues that are occurring due to the installation that is preventing your computer from properly booting up.

Disk Utility is able to fix some eros related to apps and software, so this is a good option to explore if nothing has worked so far.

Follow these steps to run your computer in recovery mode and use first aid in Disk Utility:

  • Restart your computer while holding down the Command and R keys at the same time
  • This will boot your computer into Recovery Mode, and you can access Disk Utility
  • Click on Disk Utility
  • Select a volume to repair
  • Click on First Aid
  • Click Run to begin the disk repair
  • Click Done once the repair has been made.
  • Attempt to boot the computer up to see if you can now run Big Sur

Final Thoughts

If your Mac fails to boot after installing macOS Big Sur, don’t worry. The options listed above should be able to resolve the problem fairly quickly.

If they don’t, you can always contact Apple customer service or look for some more solutions through Mac forums.

Any issues might be able to be resolved through additional software updates when they become available as well.

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  • Jonathan

    I am only able to boot in safe mode after updating to Big Sur. You noted above that, “If macOS Big Sur works in Safe Mode, you have a conflicting software program that needs to be addressed.” How do I identify the conflicting software problem and once identified, how do I resolve the conflict? Thanks!