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how do I uninstall Big Sur and reinstall Catalina?

how do I uninstall Big Sur and reinstall Catalina?

Posted on Dec 13, 2021 9:32 AM

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Question marked as Top-ranking reply

Posted on Dec 13, 2021 10:15 AM

You have to completely erase the drive then either restore from your backup or reinstall the OS. The Bootable USB option usually works best.

To completely erase the drive, you have to choose "Show all devices" from the View Popup menu, select the drive device from the list, then erase.

How to reinstall macOS - Apple Support

How to get old versions of macOS - Apple Support


2 replies
Question marked as Top-ranking reply

Dec 13, 2021 10:15 AM in response to armandofromdoral

You have to completely erase the drive then either restore from your backup or reinstall the OS. The Bootable USB option usually works best.

To completely erase the drive, you have to choose "Show all devices" from the View Popup menu, select the drive device from the list, then erase.

How to reinstall macOS - Apple Support

How to get old versions of macOS - Apple Support


Dec 13, 2021 10:20 AM in response to armandofromdoral

Below will WIPE ALL DATA and there is no Recovery - period.


To perform this action will require booting from a Bootable Installer


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 Catalina would have to be done on a computer that Qualifies to run Catalina.


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.


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.

how do I uninstall Big Sur and reinstall Catalina?

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