Mac keeps restarting over and over? Mac keeps restarting on its own? MacBook Pro keeps restarting at boot? No worry. After reading this article, you can not only know why your Mac keeps restarting (Part 1), how to fix the “Mac keeps restarting” issue (Part 2) but also how to avoid spontaneous restarts on your Mac (Part 3). If you have encountered the similar problem on your iPhone X, iPhone 8 or iPhone 8 Plus in iOS 11, go to the article about how to fix iPhone X/8/8 Plus keeps restarting to learn how to solve the problem.
In most of the cases, the main contributor to the "Mac/MacBook Pro keeps restarting" issue is "kernel panic". The "kernel" refers to the operating system of your Mac. Why does kernel panic lead to abnormal restarts? That's because the operating system has detected an issue on your Mac and the restart must be performed to fix the issue, which is usually caused by the faulty software or a problematic hardware. How to decide whether kernel panic is occurring? Generally, a message will pop up on your Mac screen showing you "Your Computer restarted because of a problem". If you are in the very situation, don't hesitate to get possible solutions in Part 2.
If your Mac or MacBook Pro keeps restarting over and over, you first need to know where the problem is. Is the software installed on your Mac the cause of the issue or the hardware on your Mac to connected to your Mac the cause of the issue? If the kernel panic is related to hardware, follow the first two tips to learn what to do. While if the problem is related to software installed on your Mac, follow the last two tips instead. (Other solutions to common Mac/iDevice problems are also covered, go to iOS & Mac Topics to find what you need if you want.)
For hardware related kernel panic:
The kernel panic could be caused by a peripheral device or a combination of peripheral devices that has been connected to your Mac or the internal RAM or third-party hardware. Thus hardware troubleshooting is inevitable to solve the "Mac keeps restarting" issue.
Step 1: Shut down your Mac and disconnect all the peripheral devices. (Keep the display, keyboard, and mouse that are from App connected only. )
Step 2: Start your Mac and use it as usual.
Step 3: Troubleshoot hardware.
Step 1: Shut down your Mac.
Step 2: Remove the third-party RAM and internal hardware from your Mac. Reseat your Apple RAM if you get one. If not, reseat the RAM you have instead.
Step 3: Start your Mac and use it as usual.
Step 4: Do troubleshooting.
For software related kernel panic:
Step 1: Use macOS Recovery to reinstall macOS.
Step 2: If you have reinstalled macOS successfully, go to App Store > Updates to install all the updates on your Mac.
Step 3: Before you reinstall the third-party software, download and install all the third-party software updates.
Step 4: Do troubleshooting.
Step 1: Use macOS Recovery to start your Mac. (Refer to step 1 in Tip 3.)
Step 2: Use Disk Utility to back up your disk image to an external drive with enough free space.
Step 3: Wipe the internal drive via Disk Utility.
Step 4: Install OS X and start your Mac from the internal drive.
Step 5: Go to App Store > Updates to install all updates on your Mac.
Step 6: Reinstall the third-party Apps on your Mac and copy the user data from the backup you have just created.
Unexpected restarts of Mac could be quite annoying, Thus it's necessary to learn how to prevent the problem from happening. The most effective way to avoid kernel panic is to always update your software to the latest version. You just need to go to App Store > Updates to make it. Easy, right? Hope you won't meet the "Mac keeps restarting" issue again. For other problems like Mac running slow, Mac stuck on the login screen, Mac won't turn on and more, you can also find the fixes in the related article.