Downgrading macOS from Big Sur to Mojave
Which installer download should I use as I need to downgrade to Mojave without a time machine backup?
iMac Pro
Do understand, downgrading from Big Sur to Mojave can be done only if the computer Qualifies to run Mojave.
To downgrade from previous and newer version like Big Sur back to Mojave will required Erasing the Entire Drive.
This is required to remove the Big Sur and replace it with Mojave.
One can not install Mojave Over Big Sur - it just will not be allowed - period.
Further, without a Time Machine Backup, to achieve the downgrade will mean ALL personal Data will be lost can not be recovered.
