iMac (2019 i9 27-inch macOS 12.4) shuts down overnight, can't be restarted unless first unplugged

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MJ Author

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143 points

iMac (2019 i9 27-inch macOS 12.4) shuts down overnight, can't be restarted unless first unplugged

There are a number of short threads on this topic that seem to just get closed before a solution is proposed.

Anyone have any suggestions for addressing this?

I have used Console to check the logs but I don't see anything strange.

The log timestamps end about 3am everyday and the resume after I force a restart the next morning.

This is hard to debug since I need to wait ~24 hours to see if a candidate fix actually works.

iMac Line (2012 and Later)

Posted on Jun 7, 2022 10:29 AM

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Answer 1

Best reply

rkaufmann87

Level 10

141,198 points

Jun 12, 2022 4:26 PM in response to MJ

It will help us get a good idea of what is causing your problem if you provide a report of your system, that way we do not have to play 20 questions with you. The report we are requesting does NOT provide any personal information and is extremely safe to use. Please navigate to www.Etrecheck.com and download the free version of EtreCheck. Once you have you downloaded the app and installed it, please run the report and save it. This report will help us get a good idea what has been installed on your system and help us be able to diagnose what may be wrong.

When you have your report, you can attach it when you reply to this message and we can then review it and help you determine what is needed to get your system running well again.

For instructions on how to download your EtreCheck report and attach it to your reply to this message please click How to use the Add Text Feature When Post… - Apple Community

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Answer 2

rkaufmann87

Level 10

141,198 points

Jun 12, 2022 11:18 PM in response to MJ

Something has modified Mac OS, there is evidence there is no Apple Security running:

Security updates are disabled.

This means you need to Install Mac OS to install the missing and damaged portions of Mac OS. Before doing this backup your system and test the back up!!!!! You can install Mac OS from the Recovery Partition.

After you have re-installed Mac OS then run Activity Monitor and leave it running and look for any run away processes. If you spot something that is likely your culprit. You are going to have to learn how to use AM so please begin with Activity Monitor User Guide for Mac - Apple Support

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Answer 3

MJ Author

Level 1

143 points

Jun 8, 2022 8:50 AM in response to MJ

Just a quick update to help ensure that this thread doesn't die in an unresolved state.

This is a single data point and NOT a sure-fire solution.

I reset my iMac's NVRAM yesterday and it did NOT shut itself down overnight.

More updates to follow.

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Answer 4

MJ Author

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143 points

Jun 12, 2022 5:57 PM in response to Allan Jones

I did upgrade the RAM back in February 2021.

Brand: OWC

Vendor B&H Photo

Specs: 32GB DDR4 2666 MHz SO-DIMM Memory Upgrade (2 x 16GB)

Total RAM now: 40GB

I will submit the etrecheck report as a reply to @rkaufmann87

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Answer 5

MJ Author

Level 1

143 points

Jun 13, 2022 5:07 PM in response to rkaufmann87

I have re-installed macOS 12.4

I also removed a USB hub that has worked for months, but I removed it for completeness.

So far the system is stable. The true test is to see if it can go overnight without shutting down.

I'll report back tomorrow.

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Answer 6

MJ Author

Level 1

143 points

Jun 14, 2022 6:29 AM in response to MJ

My iMac slept normally overnight, but it did NOT ever shut itself down.

I suspect the USB hub as being the culprit but I don't know for sure.

I will monitor this for a week or so before declaring the problem solved.

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Answer 7

MJ Author

Level 1

143 points

Jun 17, 2022 4:44 PM in response to MJ

Several days now with no overnight shutdowns.

Again, I suspect the USB hub that I was using earlier, but I have not absolute proof of that.

This is "solved" from my POV.

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Answer 8

MJ Author

Level 1

143 points

Jun 12, 2022 6:06 PM in response to rkaufmann87

etrecheck report attached

Etrecheck report iMac i9 2019

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Answer 9

MJ Author

Level 1

143 points

Jun 12, 2022 4:12 PM in response to MJ

I still have this problem. This time, it only took about one hour to shut itself down, as opposed to overnight.

So, an NVRAM reset does not appear to help in any sustained way, at least in my case.

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Answer 10

Allan Jones

Level 9

69,368 points

Jun 12, 2022 5:30 PM in response to MJ

Have you added RAM. If so, what vendor and specs?

Beyond that, your symptoms suggest a software conflict. The EtreCheck report will help us diagnose that possibility

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Answer 11

MJ Author

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143 points

Jun 13, 2022 8:44 AM in response to rkaufmann87

Thanks!

I manually control all updates on this Mac, security updates as well as "normal" updates.

I have operated this way since I purchased this Mac in late 2019.

Does that matter?

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Answer 12

rkaufmann87

Level 10

141,198 points

Jun 13, 2022 9:06 AM in response to MJ

Yes it does matter, this is a very poor practice.

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Answer 13

MJ Author

Level 1

143 points

Jun 13, 2022 9:21 AM in response to rkaufmann87

Understood.

Does it matter w.r.t. auto-shutdown?

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Answer 14

rkaufmann87

Level 10

141,198 points

Jun 13, 2022 11:56 AM in response to MJ

It may, IMHO it is not wise to try to out think Apple's engineers.

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iMac (2019 i9 27-inch macOS 12.4) shuts down overnight, can't be restarted unless first unplugged

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