Do not "start up automatically after a power failure."

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Do not "start up automatically after a power failure."

Early this morning, the power went off in my house for several minutes. I have a 2017 iMac running Ventura, 13.7. I also have the first Mac mini using the M1 chip. A few days ago I upgraded it to the new Sequoia Mac OS. The Mac mini is my future replacement. I got it a couple years ago when I thought my iMac Fusion drive had died. It turned out that there was a restore procedure that brought it back to life. Anyway, both of them were in sleep mode when the power went out. I never select, "start up automatically after a power failure." Nevertheless, both of them booted up again when the power came back on. My cursory search found nothing about this issue. I've gone through all my settings carefully. I could not find anything that might override my choice.

Has anyone else had this problem? Does anyone have a solution for this problem? I don't like having to reboot my computers on a daily basis. I normally shut them down once a week, unless I had to restart them for some other reason. And the iMac is in my bedroom. When that screen comes on in the dark, it's like having a sunrise in your bedroom. Very annoying and disruptive.

iMac 27″ 5K, macOS 13.7

Posted on Oct 17, 2024 9:20 PM

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Answer 1

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Old Toad

Level 10

210,443 points

Oct 18, 2024 11:10 AM in response to planetgazer

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following;

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

You can simulate the power outage by pulling the plug out of the wall socket to for a minute or so.

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Answer 2

planetgazer Author

Level 1

50 points

Oct 22, 2024 1:28 PM in response to Old Toad

I did that on both machines and they performed as they should after the power was cut. From now on, I will always boot up in safe mode after the power goes out. It's pretty reliable in my area but stuff happens about 3 times a year.

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Answer 3

planetgazer Author

Level 1

50 points

Oct 23, 2024 11:41 AM in response to Old Toad

Yes, after I booted up into safe mode, I did a regular restart. after it had plenty of time to get up and running, I shut the power off. When it did not start up again after I turned on the power, I rebooted into safe mode, and then did a normal shut down.

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Answer 4

Old Toad

Level 10

210,443 points

Oct 18, 2024 10:31 AM in response to planetgazer

In my opinion it's best to not have the Mac reboot automatically after a power failure. Often there can be a surge immediately after a failure and that can seriously damage a Mac that's on or booting up.

I believe it's best to let is stay off until you are able to ascertain that it's safe to reboot.

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Answer 5

planetgazer Author

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50 points

Oct 18, 2024 11:05 AM in response to Old Toad

Evidently I was not clear. I did NOT have it set to reboot after a power failure. I never do that. It just did it anyway . . . on two different Macs, running different systems. And the power was off for about three minutes.

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Answer 6

Oct 24, 2024 6:26 AM in response to planetgazer

I purposely do not let any of my Macs automatically reboot on a power outage as when it is initially restored, it may drop again in a very short time interval and I don't want the Macs subjected to this period of interruptions. Although power outages are uncommon here, they do occur and don't necessarily remain stable on restoration.

If you know you are in a spastic power delivery location, you might consider an Uninterrupted Power Supply (UPS) with wattage support for your Mac and that would give you a few minutes to correctly shut down the Mac.

See System Settings > Energy Saver > Start up automatically after a power failure.

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Answer 7

PRP_53

Level 10

91,267 points

Oct 18, 2024 1:46 AM in response to planetgazer

System Setting / Preferences >> Energy Saver

Scroll down and find >> Start up automatically after a power failure

This image is from a M2 Mac Mini running macOS 15.0.1 Sequoia

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Answer 8

planetgazer Author

Level 1

50 points

Oct 18, 2024 8:54 AM in response to PRP_53

Thanks PRP_53, but as I indicated in my original post, that is the way both of my Macs are set. They both restarted anyway. I checked after they restarted and that setting had not been changed.

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