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About unexpected restarts
Rarely, your Mac might experience a software or hardware issue that requires it to restart. When it starts up again, you might see a message that your computer was restarted because of a problem.
Sep 28, 2018 Every time I would start up or restart I would get told, “A critical software update is required for your Mac. Connect to the Internet now.” Or something to that effect. Sep 24, 2017 Ever since I installed «mac OS Sierra 10.12», whenever I use «Preview for Mac» and try to combine documents, as I used to do when I used ‘El Capitan’, «Preview for Mac» either stops working (freezes) or crashes. Under: About this Mac Utilities System Information Software Preview, it reads: Preview: Version: 9,0. Obtained from. Sep 29, 2018 The Mac has a reputation for reliability and ease of use, but crashes and freezes do in fact happen from time to time either due to performance-related issues or software bugs. It can be a nasty surprise when your Mac temporarily freezes, or worse still crashes completely (thankfully that’s a very rare occurrence), and you.
Unexpected restarts are usually caused by software installed on your Mac, or by devices connected to your Mac. If the issue causes your Mac to restart every time it attempts to start up, your Mac might eventually shut down. Use the steps below to check the software and hardware on your Mac.
Check your software
If the issue is caused by software on your Mac, one of these steps might help:
- Install all available software updates.
- If your Mac suspects that a particular app caused the restart, it might ask whether you would like to move the app to the Trash. Click Move to Trash, then contact the software developer to see if a software update is available.
- Use safe mode to try to isolate the cause of the issue.
- Reinstall macOS. If the issue continues after reinstalling macOS, check your hardware.
Check your hardware
Learn how to check your connected devices and other hardware.
Check peripheral devices first
If you don't have any devices attached to your Mac, skip to the next section.
- Shut down your Mac.
- Disconnect all peripheral devices, such as hard drives or printers. If you have a desktop Mac, make sure that only a display, keyboard, and mouse or trackpad are connected.
- Turn on your Mac.
- Use your Mac for the amount of time that it would usually take for an unexpected restart to occur.
- If an unexpected restart occurs, follow the steps to check the internal RAM and third-party hardware.
- If an unexpected restart doesn't occur, turn off the Mac and connect one peripheral device at a time until an unexpected restart occurs.
Check RAM and third-party hardware
Certain models of Mac computers have removable memory (RAM). If you recently installed memory or a hard disk (or SSD), make sure that it's compatible and installed correctly. If possible, remove it and test with the original memory or disk.
Learn more
- If you continue to experience unexpected restarts, contact Apple Support.
- If your Mac is frequently restarting unexpectedly, it's important to determine the exact steps that lead up to the issue. The next time that your Mac restarts unexpectedly, record the date and time it occurs. These questions might help you diagnose the problem:
- Was the computer starting up, shutting down or performing a particular task when the unexpected restart happened?
- Is the computer restart random or does it happen every time you do a certain task?
- Does the restart happen when a specific external device is connected to your Mac or to a specific port?
- Learn what to do if your Mac doesn't turn on or start up.
- Learn about the screens you see when your Mac starts up.
A Mac that won’t boot is a pretty useless Mac. But the situation gets worse if you have tons of data that hasn’t been backed up yet. So what do you do in these situations?
Contents
- 9 A few things to try in the future
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It’s tough to say. There could be a variety of problems causing a Mac’s boot process to fail or for the boot process to get “stuck” on the loading bar. The issue is likely fixable, but it may not be the simplest fix in all cases. Either way, here are the troubleshooting steps you should take to fix a Mac that won’t boot.
My Mac won’t turn on — now what?
This may sound obvious, but check to see if your Mac has power or if its battery needs charging.
For desktop Macs, a cable may have come unplugged. For older MacBook models, a degraded battery could cause problems that make it appear like it won’t boot.
Try Safe Mode
One of the first things to try when a Mac won’t load into macOS is to simply boot into Safe Mode.
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- Shutdown your computer. If it’s off, skip to the next step.
- Press and hold the Shift key.
- Power up your computer.
- Once you see the Apple logo, release the Shift key.
If you Mac successfully boots into Safe Mode, it may have resolved whatever boot issue it was experience. Try restarting your Mac at this point.
Reset NVRAM and PRAM
The next thing is try is to reset your NVRAM or PRAM. This is a basic troubleshooting techniques that can fix a slew of issues on your Mac.
- Shut down your Mac.
- Power your Mac back up.
- Immediately press and hold these four keys: Option + Command + P + R.
- Make sure to hold the keys for at least 20 seconds. On some Macs, you may hear a startup sound play twice or the Apple logo appear and reappear twice.
If this successfully fixed your problem, make sure to go back into System Preferences and readjust anything that was reset. That could include time zone, resolution and sound volume.
Use Disk Utility in Recovery Mode
If your Mac is booting up but is stalling on the progress bar or just won’t load into macOS, then there’s likely a software issue.
One of the first things you should do is boot into Recovery Mode and try to repair your primary drive using Disk Utility. Here’s how.
- Make sure your Mac is shut down.
- Hold down the Command + R keys.
- Power up your MAc.
- At this point, the Apple logo should pop up on your display.
- Once you see the Recovery Mode pop up, select Disk Utility from the OS X Utilities menu.
- Select the disk or partition that you have macOS installed on. (If you haven’t messed with this at all, there should only be one.)
- Click on First Aid in the top menu bar.
Once the repair process completes, you’ll want to restart your Mac to see if it fixed the issue.
Reset System Management Controller
Another more in-depth troubleshooting method involves resetting your Mac’s System Management Controller. If none of the methods above worked, then this may be a good option to try next.
It is a fairly lengthy lengthy process, and may removing your MacBook’s battery or unplugging your desktop Mac’s power cable.
In fact, because it varies depending on what Mac model you have, it’s a bit too of a process to fit here. We recommend going to Apple’s support document on the subject.
Restore From Time Machine
You can also try restoring form a previous Time Machine backup to see if that deals with the issue.
- Make sure your Mac is shut down. –
- Plug your Time Machine drive into your Mac
- Hold down the Command + R keys.
- Power up your Mac.
- At this point, the Apple logo should pop up on your display.
- Once you see the Recovery Mode pop up, select Restore From Time Machine Backup.
Reinstall macOS
If worst comes to worst, you may need to reinstall macOS. This doesn’t necessarily have to involve wiping your disk, however.
- Make sure your Mac is shut down.
- Hold down the Command + R keys.
- Power up your Mac.
- At this point, the Apple logo should pop up on your display.
- Once you see the Recovery Mode pop up, select Reinstall from the OS X Utilities menu.
- Recovery Mode will then guide you through the rest of the process.
It’s worth noting that you’ll be given the choice to erase your disk or not. While erasing will delete all of your data, it may also be more effective in dealing with software-based problems.
If you have a recent Time Machine backup, we recommend wiping your disk. If you just need to recover some data off your drive, then reinstalling macOS without wiping your disk may be the better option.
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If all else fails…
If none of the above methods work, then there is likely a deeper issue that isn’t necessarily user-fixable.
In these cases, we recommend taking your Mac or MacBook to an Apple Store or Apple Authorized Service Provider. The staff there will be able to help diagnose — and hopefully — fix any more serious software or hardware issues.
You can set up a Genius Bar appointment using this link.
A few things to try in the future
There are a number of things that may cause boot problems. Here are a few common culprits that we’ve noticed.
- Avoid bloatware. Items like Mac disk cleaners and other system maintenance tools are generally not necessary on macOS. Worse still, some of these tools can damage your MacBook’s software.
- Be careful with dual-booting. The boot loader in macOS is fairly finicky. If you try to install any other operating systems in dual-boot mode, you can damage the boot loader. If you have to run another OS on your Mac, try using a virtual machine or booting from a USB device.
- Restart your Mac periodically. According to a couple of user reports, this issue popped up when a Mac that hasn’t been restarted for a while is rebooted. While we can’t verify whether this causes the issue, it’s probably smart to restart your Mac every now and then.
Were you able to use the tips to fix the issues on your Mac? Let us know using the comments below.
Mike is a freelance journalist from San Diego, California.
While he primarily covers Apple and consumer technology, he has past experience writing about public safety, local government, and education for a variety of publications.
He’s worn quite a few hats in the journalism field, including writer, editor, and news designer.