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error while installing MacOS Monterey

I get an error while attempting to install MacOS Monterey - any ideas on how to resolve?


MacBook Pro 13″, macOS 11.6

Posted on Dec 8, 2021 7:41 PM

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Question marked as Top-ranking reply

Posted on Dec 12, 2021 8:09 AM

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 ?  


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.

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Question marked as Top-ranking reply

Dec 12, 2021 8:09 AM in response to The Big E

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 ?  


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.

Dec 9, 2021 1:20 AM in response to The Big E

What is the exact wording of the error message?

Where in the update process are you getting that message?

Possible problems:


You need an Apple disk installed to upgrade to Monterey since the upgrade includes an update to the Mac's firmware. That update looks for an Apple disk and write to the dick to do the firmware update. The install will terminate or freeze if no Apple disk.

Do you have enough free disk space?

  • If upgrading from macOS Sierra or later, your Mac needs 26GB of available storage to upgrade. If upgrading from an earlier release, your Mac needs up to 44GB of available storage.

Do you have any antivirus or clean apps installed? Id so uninstall them udding the app's instructions.


Dec 12, 2021 8:22 AM in response to The Big E

If possible to get an Original Apple Drive and flip out the After Market drive and pop in the Original drive - format etc and run the Monterey Installer to that drive. Then, reverse the previous step and run the Monterey Installer again to the after Market Drive.


Presto - Monterey should install.


Credit to @ lllaass for discovering this work around.



error while installing MacOS Monterey

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