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Down-or-Back-grading my OS from Monterey to Big Sur

If I want to do that-downgrade from Monterey to Big Sur-where do I start? I don't think I've tried that before, but I know that creating ANY bootable disc now is more complicated than it used to be. Now, apparently, it must be done with Thunderbolt equipment rather than mere standard-issue USB ports and cables. What I'm using right now is Monterey 12.3.1, and I would like to have both Big Sur and Monterey to boot from, but I know that Big Sur can't be added with Monterey in the driver's seat. So where do I start?

Mac mini 2018 or later

Posted on Apr 18, 2022 6:55 AM

Reply
Question marked as Top-ranking reply

Posted on Apr 18, 2022 7:09 AM

This method will WIPE ALL Data and there is No Recovery - Period.


To perform this action will require booting from a Bootable Installer


Have created Bootable Installers all the way from Monterey 12.3.1 down to High Sierra 10.13.6 lately and all done to USB 16 GB Flash Drive - all these work fine.


This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of Big Sur would have to be done on a computer that Qualifies to run Big Sur.


Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can not be used.


Once that is done read on for preparing the Destination computer 


>> Only works on Intel Based Apple Computers.


Extra Special Notation regarding the Touch ID equipped Apple Computer.


About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting 


1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.


2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 


3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 


4 - Choose the Upper Most Drive ( not the volumes indented and list below ).


5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map. This applies to macOS 10.14 Mojave and above. 


6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 


7 - Follow the prompts and it may automatically reboot several time. 


8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.

2 replies
Question marked as Top-ranking reply

Apr 18, 2022 7:09 AM in response to Birck Cox

This method will WIPE ALL Data and there is No Recovery - Period.


To perform this action will require booting from a Bootable Installer


Have created Bootable Installers all the way from Monterey 12.3.1 down to High Sierra 10.13.6 lately and all done to USB 16 GB Flash Drive - all these work fine.


This will have to be performed from a Qualifying Computer to run the version of macOS to be made on the Bootable Installer. Example : Bootable Installer of Big Sur would have to be done on a computer that Qualifies to run Big Sur.


Notation: If the computer being used to perform this action is Too New or Too Old to qualify to run the version of macOS - this computer can not be used.


Once that is done read on for preparing the Destination computer 


>> Only works on Intel Based Apple Computers.


Extra Special Notation regarding the Touch ID equipped Apple Computer.


About Startup Security Utility and Must Enable from Recovery Mode the ability to boot from External Drive Before Attempting 


1 - Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.


2- Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive. 


3 - It will present options >> Disk Utilities >> View >> View ALL attached Drives. 


4 - Choose the Upper Most Drive ( not the volumes indented and list below ).


5 - The drive normally is called Apple Media or Apple SSD - that is the drive to Erase and format as APFS with the GUID Partition Map. This applies to macOS 10.14 Mojave and above. 


6 - Once that is done >> backup out of Disk Utilities and choose install macOS. 


7 - Follow the prompts and it may automatically reboot several time. 


8 - Upon a final reboot - Setup Assist will present with the newer version of macOS.

Down-or-Back-grading my OS from Monterey to Big Sur

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