[OFF] Inopportune Auto-Restart of the Mac

My Mac tries to restart automatically several times a day, which is very annoying; I’ve read dozens of pages on the internet, including Apple’s website, without being able to solve the problem.
It’s an illness that happens for months and then disappears (like the flu!) and then reappears.
It’s not a crash; fortunately 4D saves me, you can see that it’s not completely off topic!
It happened with High Sierra but also with Mojave.
I have no error message; macOS closes all possible applications except 4D and Firefox which asks permission to close the tabs.

There are so many skills on this list that I ask if anyone would have an idea.


Have you checked your Mac with Malwarebytes?


Walt Nelson (Seattle)



Open /Applications/Utilities/Console and look at the system log around the time it tries to shut down. Hopefully there should be some clues.

Also check Energy Saver control panel and click on the “Schedule” button. Make sure you don’t have a scheduled shutdown.

I feel fortunate that I have never had to deal with such problems with my Apple hardware, it certainly sounds awful.

That said, my MacBook Pro has been “cursed” and has the habit of never waking up the built-in keyboard or trackpad after waking up from sleep. I must use the power switch to shut everything down. Evidently, it is quite common malfunction with MacBook Pro (you can Google about it).

I have tried PRAM reset, other kinds of resets, trashing different .plist files. As of today, the problem still exists.Also, the Sidecar double screen feature is really unreliable on this computer and my iPad Pro. Again, found lots of posts on the internet by people having the exact same problem.

The point of this post is that I feel it is the new reality, that Mac has become so complicated and highly customisable, that these kinds of issues will pop up from time to time. On the positive side, we can seek help from a much larger community.

Have you searched for clues in the wider Apple user community?


I think this post will be very interesting for you

Good luck to catch your problem :wink:

Yes Walt : nothing, rien, nada, que dalle !

It always did this to me when I turn my back!

Same for me.

No scheduled shutdown ; I never had one.
Energy saver is turned on.

You might have a hardware problem. Restart holding the “D” key might help to see: https://support.apple.com/en-us/HT202731

My last hypothesis: I had the same problems under High Sierra; I switched to Mojave and it stopped; now my Mac finds Mojave outdated and wants to switch to Catalina!

I also use EtreCheck in free version …

Off course, Google is the first tool to use.

Overheating can cause a Mac to suddenly shut down to protect itself.

Does your Mac have adequate ventilation? Does CPU get to 100 degrees Celsius before it turns off?

Anything in Console logs?


It’s a MacBook Pro ; the fans do not turn very fast.

I never used Console ; at next restart, I will have o look to the logs…

I tried it and got an error DEC400, seems well known…
Alt D at restart gives another error, alsp well known…

I think support for the “D” test started in 2014. Option-D requires an internet connection.
You could try Safe boot, and then restart after it comes up to the login or Desktop. Safe boot (start with shift key down) repairs the directory and cleans some caches. https://support.apple.com/en-us/HT201262

When I had a 17" MacBook Pro some years ago, for quite some time it would often not wake the screen from sleep if I had run Xcode. I could ssh into it and kill the login console process, and it would kill all my apps/processes and wake the screen at the login prompt.

I can’t remember if that problem eventually resolved itself with newer versions of Xcode or a newer computer.

My current MacBook Pro 16" has given me an error about having no mouse/keyboard attached when waking up from sleep. Closing the lid and re-waking fixed it.