How to Fix iMac Shutdown Problems From the Mojave 10.14.3 Update

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Have you tried restarting your iMac after updating to Mojave 10.14.3 but it got stuck and won’t shut down? If that is the case, you are not alone. For many iMac users, an iMac not shutting down after the Mojave update is becoming a popular problem.

In this article, we look at some ways on how to fix problems with an iMac that won’t shut down after the Mojave update.

1. Close All Active Apps.

For your iMac to properly shut down, you need to close all active apps first. Problems with shutting down iMacs often arise due to apps that fail to close. So, before you do any troubleshooting steps, check if any app is still open. An app isn’t likely to close if a change has been made but remains unsaved.

If you have already saved the changes but the app still does not close, you have to force-quit it. To do that, try any of these options:

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  • Right-click on the icon of the app in the Dock. Select Force Quit.
  • Hold the Command, Option, and Escape keys together and click the app in the Force Quit Hit the Force Quit button.
  • Open the Apple Choose Force Quit. Choose the problematic app and hit Force Quit.
  • Right-click on the icon of the app in the Dock and hold down the ALT You’ll see that the Quit button changes to Force Quit. Click on it.
  • Open the Activity Monitor and close the app from there.

2. Perform an Apple Hardware Test or Apple Diagnostics.

Apple Hardware Test and Apple Diagnostics are two handy built-in tools that help you troubleshoot problems with your iMac. These tools can investigate problems with your system memory, wireless components, and even the logic board. If your iMac won’t shut down after the Mojave 10.14.3 update, you might want to try running any of these tools.

Using Apple Hardware Test and Apple Diagnostics is easy. But running them, you have to figure out which tool is appropriate for your macOS version and your iMac model. To know these details, open the Apple menu and click About This Mac. From there, check the following:

  • If your iMac’s version is from 2013 or later, then use Apple Diagnostics since it is already built into your machine.
  • If your iMac’s version is from 2012 or earlier, use Apple Hardware Test.

Using Apple Diagnostics

  1. Disconnect all external peripherals except the display, mouse, and keyboard.
  2. Go to the Apple menu and select Restart.
  3. Hold the D key while waiting for your iMac to restart.
  4. Apple Diagnostics should begin automatically. Follow the on-screen instructions.
  5. Once the test is done, all the problems found will be shown on your screen.

Using Apple Hardware Test

  1. Disconnect all external peripherals except the display, mouse, and keyboard.
  2. Go to the Apple menu and choose Restart.
  3. Hold the D key while waiting for your iMac to restart.
  4. Once the Apple Hardware Test screen appears, choose the language you want to use.
  5. Press Return.
  6. If the Apple Hardware Test screen does not show, you have the option to run the test online. You need to connect your iMac to a stable internet connection and restart your Mac while pressing and holding the Option and D keys.
  7. Follow the on-screen instructions.
  8. If a problem is detected, you will be notified of it. Take note of the message and seek further assistance from Apple Support.

3. Safe-Boot Your iMac.

Performing a safe boot can delete your system cache and help improve your system after an update. So if you have just updated to the most recent Mojave but iMac is not shutting down, then you should try this solution.

Here’s how to safe-boot your iMac:

  1. Since you cannot shut down your Mac properly, do anything you can to switch it off.
  2. After that, wait for 10 seconds before pressing the Power button.
  3. Once you hear the startup tone, press the Shift key. Hold it down until the Apple logo appears.
  4. At this point, you have entered Safe Mode. With this mode enabled, all extensions are disabled and other unnecessary apps are not running. Take note that it may start slow, so give it time.
  5. If your iMac works fine in Safe Mode, restart it, but this time in a Normal setting.

4. Clear Your System of Junk Files.

One possible reason why your iMac is acting up upon shutdown is that there’s plenty of junk files that are interfering with your system processes. It’s a wise move to get rid of them.

To delete junk files, you can manually go through all your folders and delete the files you don’t need. But we won’t suggest doing this because you might accidentally delete important system files and trigger more errors and problems. It’s also time-consuming.

What we highly recommend doing is to download and install a third-party iMac cleaning tool. In just a few clicks, you can instantly find junk files and delete them as you like. It won’t even take you hours to do that. Be careful, though, because there are cleaning tools out there that are bundled with malware and viruses. It is best that you read reviews first or seek recommendations.


Most power-related errors on iMacs are usually fixed after performing Apple Diagnostics or Apple Hardware Test. If not, a Safe Boot or the use of third-party cleaning tools might address the problem. However, if you are not confident with your skills in resolving the problem, you can consult an Apple expert. He or she can figure out the problem and suggest the perfect solutions for you.

We hope what we shared above have helped you resolve your iMac shutdown problems caused by the recent Mojave update. We’d like to know which of the solutions worked for you. Share them below!

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