Fix Mac not booting after macOS update (The Definite Guide)

By Jenny> | Posted to Home > Mac Data Recovery Tips, updated on June 8th, 2021 |

Apple releases macOS and software updates periodically for better user experience. However, it backfires when your Mac won't boot after a macOS update. You may see a black screen on Mac, or encounter other screen of death issues.

The Mac won't turn on after update drives you crazy because it blocks you from using Mac. More importantly, you can't access all data on your Mac.

Take it easy. This post will help you retrieve data from the unbootable Mac and walk you through the iMac or MacBook not working after update issue.

Fix Mac won't turn on after macOS update

Recover data from Mac that won't turn on after macOS update

Note: Usually, it is advised to recover data from your Mac first, and then fix the unbootable Mac. That's because your attempts to fix this issue will write new data on your Mac, which will overwrite the old data and lead to permanent data loss.

Don't hesitate. Follow the detailed data recovery tutorial in this video to recover data stored on the Mac that not booting up.

To recover data from the Mac that can't start up, data recovery software is necessary. iBoysoft Mac Data Recovery, a software with a high data recovery rate, fully supports recovering data from corrupted, unmountable, and unreadable Mac hard drive and various external hard drive.

As your Mac won't start up, you need to run iBoysoft Mac Data Recovery in macOS Recovery mode to recover files from your Mac. Or, you can follow the video instead, which is visualized.

What to do when Mac won't turn on after update?

Here are some proven efficient solutions for fixing iMac or MacBook that won't restart after update to macOS Monterey, Big Sur, macOS Catalina, macOS Mojave, or earlier macOS versions.

Check the power connections

Sometimes, your Mac won't turn on after an update is simply due to the lack of power or power outage. Press the power button. Then, check if you can hear a startup chime or fan or drive noises or not.

If you can't hear any noise, your Mac has power connection issues. Just try these fixes:

  • Make sure the wall outlet, charger cable, or adapter is okay.
  • If you use a MacBook, charging the battery for a while to avoid it's dead.
  • Press the power button again to restart your Mac.

If you can hear the startup chime but Mac still won't boot, try to do a Power Cycle. Power Cycle allows fully cutting all traces of power from the Mac, and then restarting the Mac from scratch.

To perform a Power Cycle:

  • For a MacBook without a removable battery, press the power button and hold it down for ten seconds. Then, restart your Mac.
  • For an iMac or Mac mini, unplug the power cable, leave it unplugged for ten seconds, and then plug it back in and restart the Mac.

Then, your Mac can turn on normally.

Disconnect all peripherals

Rare but not impossible - the external accessories connected to your Mac lead to the Mac not starting up normally. You can unplug the recently plugged external hard drive or other devices, or unplug all the peripherals at once. Then, restart your Mac to check if the peripherals cause this issue.

Reset SMC

SMC (System Management Controller) takes charge of your low-level settings, like thermal and battery management. So, reset SMC on your Intel-based Mac via pressing down Control + Option + Shift keys during Mac rebooting. This will give a chance to fix the unbootable Mac.

Reset the PRAM / NVRAM

PRAM (Parameter Random-Access Memory) and NVRAM (Non-volatile Random-Access Memory) are small memories on your Mac. They are used to store certain settings, including startup-disc selection, recent kernel panic information, and more.

To fix the Mac that won't boot up after the update, resetting PRAM/NVRAM (hold down the Command + Option + P + R keys at startup) sometimes works.

Note: For an M1 Mac, NVRM is automatically running tests and resetting at startup if needed.

Boot your Mac into Safe Mode

Mac won't restart after a macOS update? Check if any program is not compatible with your updated macOS. Safe Mode is a decent helper to do this checking. It will only launch some basic necessary programs at the startup. And it's easier to isolate incompatibility software that makes your Mac unbootable.

Make sense, right? Then let's dive into details on how to do this.

To boot an Intel-based Mac into Safe Mode:

  • Press and hold the Shift key when restarting your Mac.
  • Release the key until you see the login window.

To boot an Apple M1 Mac into Safe Mode:

  • Shut down your Mac.
  • Hold down the power button until the startup disks and Options appear on the screen.
  • Select your startup disk and press and hold the Shift key, then click Continue in Safe Mode.

If you boot into Safe Mode successfully, you'll see Safe Boot at the right top. At least, it indicates that the macOS update is not failed. Then, the troublemaker should be third-party software incompatibility.

boot into mac safe mode

But to figure out exactly which program makes your Mac unbootable, you need to reboot into Verbose Mode. Verbose Mode allows you to see what's happening during macOS booting up.

To enter into Verbose Mode, you need to shut down your Mac and hold Command + V at startup. Then you'll see a live report when your Mac booting. Once you find out the culprit, you can simply uninstall the apps in Mac Safe Mode.

boot into mac verbose mode

Boot into macOS Recovery mode

If you fail to boot into Safe Mode, it means that your Mac won't boot result from a macOS update failure. Maybe the APFS reformatting process was interrupted, so the system is damaged or broken. Or the Mac hard drive is corrupted for bad sectors.

How to Boot into & Use M1 Mac Recovery mode

In this case, you can try to repair the hard drive with Disk Utility under Mac Recovery mode. Running First Aid in Disk Utility helps Mac boot up in some ways since it's the built-in free disk repair tool on your Mac.

Boot Mac or M1 Mac in macOS Recovery mode

If your Mac still won't boot after running First Aid, you should reinstall the macOS in macOS Recovery mode.

Simply return to the Disk Utilities window and choose Reinstall macOS. If you don't want to update macOS anymore, you can try your luck with using APFS snapshot to recover your system.

Note that macOS reinstallation will risk your data on the Mac. Thus, you should firstly recover data with iBoysoft Data Recovery for Mac from the unbootable Mac.

Tips: You can prevent APFS conversion with start to install this time if you want to avoid unnecessary problems. But you are not advised to unless you are a Mac command geek.

Ask Apple repair store for help

The toughest thing is that your hard drive is fine. And there is no software incompatibility noticed in Verbose Mode. In this case, you should check the hardware inside your Mac.

The reason is that macOS updates are always for better supporting the latest software and hardware. So, the hardware or drivers on your Mac may be too outdated to work with the newer OS.

In this case, you can ask for help from the Apple repair store and reset the Mac. If it's the Mac machine itself that is too old, you should replace it with a newer Mac model. Or you simply don't allow automatically update the macOS.

Common boot problems after macOS update

For most Mac users, there are four systems commonly used: macOS Monterey, macOS Big Sur, macOS Catalina, macOS Mojave, and macOS High Sierra. Nevertheless, updating each of them could cause problems.

1. Mac won't boot after macOS Monterey update

The newest major release of Mac operating system is macOS 12 Monterey. Though there are some powerful features on macOS 12, it also has the known boot issues of macOS Monterey and how to fix them.

2. Mac won't turn on after macOS Big Sur update

Up to now, the known boot issues of macOS Big Sur include the following, or more.

  • If you updated to macOS Big Sur 11.0 but not the newest vesion, it has some existing bugs.
  • macOS Big Sur stuck on a boot loop.

3. Mac won't start up after macOS Catalina update

Then it comes to macOS Catalina. Catalina update problems like Mac won't boot after macOS update still occur.

Except for APFS conversion, the macOS Catalina update will automatically divide your hard drive into two volumes. One is the read-only Macintosh HD system volume, and the other is Macintosh HD - Data for saving your files. But if there is not enough free space for an update, you'll get an update failure. What's worse, you might see the Mac folder with a question mark at startup because the macOS Catalina update is not found.

Besides, the 'Full Disk Access' permission might be a lion in the way for some unauthorized applications. For instance, you have a program that requires certain Kernel extensions. But after updating to macOS Catalina, this program can't access the Kernel resource anymore. It doesn't have permission. As a result, your Mac will be frozen at the loading bar because this program keeps asking for resource permission.

4. Mac won't restart after macOS Mojave update

As you might know, Apple introduced the System Integrity Protection (SIP) feature since OS X EI Capitan. It was originally introduced to keep system security. But once this feature was disabled previously before you update to macOS Mojave, it could cause boot problems.

For example, the Google software update on September 23, 2019, was shipped with a bug. This flaw damages the macOS file system on computers where System Integrity Protection is disabled. Many video professionals reported that their Mac crashed due to this.

So, just think about it, even Google can't avoid such software conflict, how about other third-party software? That's one of the reasons why many users who disabled SIP previously get Mac crashed after installing macOS Mojave.

5. Mac won't boot after macOS High Sierra update

One of the major updates in macOS High Sierra is the introduction of the Apple File System (APFS). As a part of the upgrade process, the macOS High Sierra installer will automatically convert the SSD to the APFS file system.

APFS cause problems after macOS update

Even though Apple claims that the conversion process is supposed to be risk-free, many Mac users still meet problems. And the disk corruption during the update is one of them.

In this case, it's sure that the Mac won't restart after the update. Mac will stop loading after the update for such corruption. Or, the Mac won't let you log in with the right password. Also, the Mac could freeze on a black or white screen of death.

Why is the Mac not turning on after update?

Why Mac won't update successfully? It's fair enough to say, most of the time, Mac won't turn on after a macOS update because of update failure, software incompatibility, and bugs.

As new programs and hardware to be released constantly, your Mac needs to update to work with the new software and hardware. Sometimes, it's an overall macOS update. And sometimes, it's a tiny patch like this.

Mac update is available

In detail, a macOS update could involve those activities.

  1. Upgrade certain necessary drivers. Sometimes, it simply installs patches to fix bugs. But sometimes, it will replace the whole driver structure to better use hardware.
  2. Upgrade the Kernel programs. Such updates will improve the security, accessibility, and management of core data.
  3. Redesign or update certain built-in applications. Utilities like Disk Utility, Safari, and Mail come along with the operating system.
  4. Other updates like operating system structure, file system, user interface, etc.

These updates are usually for a better user experience. Or they are for better supporting most of the latest hardware and software. However, as it is pointed out, the updated macOS can only work "most" of them.

For example, Nvidia GTX 750 Ti can't work with Mac OS X earlier than Yosemite. After such a software update, Mac is not working, or the Mac or MacBook stuck on loading screen after macOS update. Once the third-party software and hardware on your Mac won't work with the latest macOS, your Mac won't turn on.

How to avoid macOS update failure?

Avoid Mac crash before macOS update

Every time there is a new macOS update available, you'll receive a notification. It asks "Do you want to restart to install these updates now or try tonight?". However, it's not safe to update directly because your Mac could get stuck on updating or even lose important files.

In case the Mac won't boot after macOS Monterey or Big Sur update, you surely can do some preparations in advance.

  • Read several reviews from tech enthusiasts to learn problems when a new macOS beta is released.
  • Make sure your Mac model and its hardware work with the updated macOS.
  • Read macOS update instructions carefully when you are up to update your system.
  • Back up your files, photos, documents, etc.
  • Make sure there is enough free disk space for macOS updates.
  • Make sure your Mac is connected to power to avoid the black screen of death during the macOS update.

Final thoughts

When your Mac won't turn on after an update, please calm down. Follow this guide to recover data from your Mac with iBoysoft Data Recovery for Mac and fix this issue. If you have any other feasible solutions to enrich this article, kindly drop us a hint at [email protected]