My computer will not restart after Monterey update

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My computer will not restart after Monterey update

I have a 2018 iMac. In early 2021 I bought an external drive (G-drive) and I run the OS on that SSD. My computer prompted me to do an update yesterday to upgrade to Monterey. My computer will not restart. The result is the same whether I press and release the power button, or keep it pressed throughout the cycle: I see the Apple logo, then in six languages a notice that says “Your Computer restarted because of a problem. Press a key or wait a few seconds to continue starting up.” Then I see a progress bar, but the startup cycle begins again. After a few cycles I see a circle with a line through it (a prohibitory symbol) and “support.apple.com/Mac/startup before the screen goes dark.

I have a third-party Bluetooth keyboard (my original Apple keyboard is in storage), which might present a problem with trying to start in safe mode. I’d appreciate any advice.

iMac 21.5″ 4K, 12.5

Posted on Sep 15, 2022 8:53 AM

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Answer 1

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PRP_53

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91,819 points

Sep 15, 2022 1:55 PM in response to LakeElmoJG

What version of macOS is presently installed on the Internal Drive ?

Starting the computer in Recovery Mode ( two key combo command + r ) with a Wired Keyboard and choose Reinstall macOS will hopefully work.

It will require an active and functional Internet Connection ( Ethernet Cable to Router is best ). It should bring down the version of macOS associated with the Recovery Volume on the Internal Drive

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Answer 2

LakeElmoJG Author

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Sep 15, 2022 11:33 AM in response to PRP_53

Thank you; that makes sense, that the external drive is the problem.

Can you or anyone else recommend a way to undo my failed installation of Monterey—especially because I can’t restart my computer? I could just refrain from installing Monterey at all now.
I got the 2T external drive last year because my computer was slow. Would installing Monterey on the original drive be possible at all?

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Answer 3

PRP_53

Level 10

91,819 points

Sep 15, 2022 10:37 AM in response to LakeElmoJG

There are reports appearing on the ASC Forums regarding failed installation of Monterey on older Qualifying Apple Computers. In most cases this is related to having a NON Apple Original Internal Drive ?

In your case, the External Drive would apply

The EFI Boot ROM included in Monterey is verifying for Original Apple Drive and if not found , may Balk or fail to upgrade to Monterey.

Reports indicate the EFI BOOT ROM is Required to Flash the Computer and is a requirement for a Successful Monterey Installation

Possible Solution is Install Monterey Directly to Internal Drive and there after the External Boot Drive Amy or may not function.

Booting Monterey from a Bootable External Drive as become very problematic at best.

It can be done but not too reliable and a lot of trial and errors

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Answer 4

LakeElmoJG Author

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9 points

Sep 15, 2022 2:47 PM in response to PRP_53

Thank you. The wired keyboard (powered on!) was key to my being able to restart in recovery mode. I just tried to restore from Time Machine, having selected my most recent backup from yesterday. That brought me back to a cycle of failed restarts.

Now I’ve opened “About Startup Disk” and can see my internal drive (Macintosh HD) has macOS 11.2.3 installed, while my external drive (SSD for macOS) has macOS 12.6 installed.

I can choose Reinstall macOS Monterey and select the internal drive if that is what you recommend.

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Answer 5

PRP_53

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91,819 points

Sep 16, 2022 1:50 AM in response to LakeElmoJG

Q - " Now I’ve opened “About Startup Disk” and can see my internal drive (Macintosh HD) has macOS 11.2.3 installed, while my external drive (SSD for macOS) has macOS 12.6 installed. "

A - Thank you for the crucial piece of information.

A - Before moving forwards, suggest discounting All External Drives from the computer.

A - As the Internal Drive already has an older version of BIG SUR 11.2.3.

A - Booting into Recovery Mode and choosing the Reinstall macOS it will probably bring down a Newer or Newest version of Big Sur. The Newest version being Big Sur 11.7

A - There after - one can choose the upGrade the Internal Drive to Monterey. That would satisfy the EFI BOOT ROM being Flashed to the Computer ( Not the Drive itself )

A - As for the Present External Drive containing Monterey 12.6, it may or may not function again as a Bootable External Drive for reasons previously outlined.

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Answer 6

LakeElmoJG Author

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9 points

Sep 16, 2022 9:30 AM in response to PRP_53

I thank you very much for your reply. By the time I read it, though, I had already chosen to install Monterey on the internal drive. It took 2-1/2 hours, but it was successful. Today my computer is very slow (it takes five minutes to open a Word document and it takes almost a minute to open a new Mail message). So I am generating at EtreCheck report and when it’s ready I will start a new thread in the ACS forums in order to resolve the new problems. Again, thank you!

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Answer 7

PRP_53

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91,819 points

Sep 20, 2022 9:17 AM in response to LakeElmoJG

Good work and you are one of the few who has successfully installed Monterey to an external drive ( be it a Clone Copy using the Legacy Method from CCC ) or directly to external and make is Bootable.

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Answer 8

PRP_53

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91,819 points

Sep 20, 2022 2:07 AM in response to LakeElmoJG

OK

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Answer 9

LakeElmoJG Author

Level 1

9 points

Sep 20, 2022 8:29 AM in response to PRP_53

I want to follow up: Monterey was taxing my 5400 RPM internal drive, so I cloned my internal drive to an external SSD and made the external SSD the startup disk. All is well.

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My computer will not restart after Monterey update

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