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How to Fix a Mac that Keeps Rebooting

Authored by:
Support.com Tech Pro Team
This Guided Path® was written and reviewed by Support.com’s Tech Pro team. With decades of experience, our Tech Pros are passionate about making technology work for you. We love feedback! Let us know what you think about this Guided Path® by rating it at the end.

Introduction

If you've ever experienced a black and grey kernel panic screen, it can be very abrupt and frustrating. When an app has a problem, you may simply see a spinning wheel cursor, but when multiple apps fail - or the operating system fails itself - you may experience a kernel panic.
This guide will take you through some steps that can help you overcome an unexpected kernel panic error. The steps are listed in order, so start with the first one, see if that helps, and then continue with the next one if it doesn't.
macOS kernel panic

1 Force Restart the Mac

If your Mac computer is showing a Kernel Panic screen, is frozen or not responding, you may need to forcefully restart it.

This works nearly the same on any modern Mac, with the difference being whether the Mac has a physical power button on the back of the machine or if it is a MacBook, where the power button is a part of or slightly above the keyboard.

  1. Hold down the Power button on the Mac until it shuts down completely, this may take 5-10 seconds or so.
    iMac rear-facing power button.
  2. Wait a few seconds then press the Power button again to boot the Mac.
    MacBook power button on the keyboard.

2 Check for Updates

  1. Select the Apple menu, then App Store.
    macOS Mojave Apple Menu with App Store highlighted.
  2. You will now see the app store pull up. Select Updates.
    If Your Mac is Running 10.14 Mojave or Later App Store side bar with Updates highlighted.
    If Your Mac is Running 10.13 High Sierra or Earlier App store menu bar with Updates highlighted.

Any version of macOS 10.7 (Lion) or older can check for available updates through the Apple Menu and Software Updates.

3 Check Startup Programs

  1. Select the Apple Menu and then System Preferences.
    macOS Mojave Apple Menu with System Preferences highlighted.
  2. Select Users & Groups.
    macOS Users and Groups Preferences
  3. Select Login Items at the top, then your Username on the left. Finally, select the lock in the bottom-left corner to unlock these settings.
    Users and Groups Preferences with Login Items, User, and Lock highlighted.
  4. Enter your macOS password, and select Unlock.
    System Preferences unlock prompt with password and Unlock button highlighted.
  5. Look through the list on the right. If you see an item you don't recognize, or an item you don't use frequently, highlight it by clicking its name, then click the Remove (–) button below to remove it.
    Users and Groups Login Items with an item and minus button highlighted.

4 Reinstall macOS

When you've exhausted all options in trying to fix a major issue with your Mac computer, you may be left with having to reinstall macOS to bring it to its original state it was in out of the box.

Reinstalling macOS will remove all customization, files, and programs on your computer. Make sure you have a recent backup before proceeding.

Back Up All Personal Data
  1. Select Apple Menu > Restart.
    macOS Mojave Apple Menu with Restart highlighted.
  2. Immediately after your Mac restarts (some Mac computers play a startup sound), press and hold the command ⌘ and R keys until the Apple logo appears, then release the keys.
    Mac keyboard with command and R keys highlighted
  3. Highlight Reinstall macOS, then select Continue.
    macOS Utilities with Reinstall macOS and Continue button highlighted
  4. macOS setup will begin. Select Continue.
    macOS Install with Continue highlighted.
  5. Select Agree to accept the Terms of Service.
    macOS Terms of service with Agree highlighted.
  6. Select Agree to confirm you agree with Terms of Service.
    Terms of Service dialog with Agree highlighted.
  7. Choose a Drive to install macOS on and select Install.
    macOS install drive selection with drive and Install highlighted.
  8. Install will now start and this will take some time. The computer will reboot during this process.

If the Issue Persists

Please contact the product manufacturer for further assistance.

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If you've ever experienced a black and grey kernel panic screen, it can be very abrupt and frustrating. When an app has a problem, you may simply see a spinning wheel cursor, but when multiple apps fail - or the operating system fails itself - you may experience a kernel panic.
This guide will take you through some steps that can help you overcome an unexpected kernel panic error. The steps are listed in order, so start with the first one, see if that helps, and then continue with the next one if it doesn't.
macOS kernel panic

If your Mac computer is showing a Kernel Panic screen, is frozen or not responding, you may need to forcefully restart it.

This works nearly the same on any modern Mac, with the difference being whether the Mac has a physical power button on the back of the machine or if it is a MacBook, where the power button is a part of or slightly above the keyboard.

  1. Hold down the Power button on the Mac until it shuts down completely, this may take 5-10 seconds or so.
    iMac rear-facing power button.
  2. Wait a few seconds then press the Power button again to boot the Mac.
    MacBook power button on the keyboard.
  1. Select the Apple menu, then App Store.
    macOS Mojave Apple Menu with App Store highlighted.
  2. You will now see the app store pull up. Select Updates.
    If Your Mac is Running 10.14 Mojave or Later App Store side bar with Updates highlighted.
    If Your Mac is Running 10.13 High Sierra or Earlier App store menu bar with Updates highlighted.

Any version of macOS 10.7 (Lion) or older can check for available updates through the Apple Menu and Software Updates.

  1. Select the Apple Menu and then System Preferences.
    macOS Mojave Apple Menu with System Preferences highlighted.
  2. Select Users & Groups.
    macOS Users and Groups Preferences
  3. Select Login Items at the top, then your Username on the left. Finally, select the lock in the bottom-left corner to unlock these settings.
    Users and Groups Preferences with Login Items, User, and Lock highlighted.
  4. Enter your macOS password, and select Unlock.
    System Preferences unlock prompt with password and Unlock button highlighted.
  5. Look through the list on the right. If you see an item you don't recognize, or an item you don't use frequently, highlight it by clicking its name, then click the Remove (–) button below to remove it.
    Users and Groups Login Items with an item and minus button highlighted.

When you've exhausted all options in trying to fix a major issue with your Mac computer, you may be left with having to reinstall macOS to bring it to its original state it was in out of the box.

Reinstalling macOS will remove all customization, files, and programs on your computer. Make sure you have a recent backup before proceeding.

Back Up All Personal Data
  1. Select Apple Menu > Restart.
    macOS Mojave Apple Menu with Restart highlighted.
  2. Immediately after your Mac restarts (some Mac computers play a startup sound), press and hold the command ⌘ and R keys until the Apple logo appears, then release the keys.
    Mac keyboard with command and R keys highlighted
  3. Highlight Reinstall macOS, then select Continue.
    macOS Utilities with Reinstall macOS and Continue button highlighted
  4. macOS setup will begin. Select Continue.
    macOS Install with Continue highlighted.
  5. Select Agree to accept the Terms of Service.
    macOS Terms of service with Agree highlighted.
  6. Select Agree to confirm you agree with Terms of Service.
    Terms of Service dialog with Agree highlighted.
  7. Choose a Drive to install macOS on and select Install.
    macOS install drive selection with drive and Install highlighted.
  8. Install will now start and this will take some time. The computer will reboot during this process.

If the Issue Persists