edmondo17 wrote:
Given that Big Sur has several incompatibilities with the programs I use, I would like to return to the previous configuration, but how do I reinitialize the HD to the Mac OS Extended format?
Starting in macOS 10.15 Catalina and above versions of macOS
All version must have the Drive formatted in APFS and no older support running the Operating System in HFS Extended Journaled format - full stop
Return to previous configuration meaning reverting back to macOS 10.13 High Sierra ?
This method will WIPE ALL Data and there is No DATA Recovery - Period.
To perform this action will require booting from a Bootable Installer.
The Bootable Installer can Only be performed on an Apple Computer
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 High Sierra would have to be done on a computer that Qualifies to run High Sierra.
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’t be used.
Alternative is, to gain access to a Qualifying Apple Computer from a family member, friend or associate.
Shutdown computer and disconnect all external drive Except the newly created Bootable Installer.
Restart and immediately hold the OPTION key until the Startup Manager appears and choose the USB Drive.
It will present options >> Disk Utilities >> View >> View ALL attached Drives.
Choose the Upper Most Drive ( not the volumes indented and list below ).
Formatting for macOS 10.13 High Sierra and below requires HFS Journaled with the GUID Partition Map
Once that is done >> backup out of Disk Utilities and choose install macOS.
Follow the prompts and it may automatically reboot several time.
Upon a final reboot - Setup Assist will present .
You can use Setup Asset and point it to the Time Machine Backup Drive.
