I'm trying to downgrade from Monterey to BigSur on an iMac with T2.
I've already enabled in security boot from external devices.
I've created a working bootable usb with BigSur, but,
when I try to boot from option it sees the usb disk with big sur, and let me choose it, but comes back to internet recovery in monterey.
Guess what I've missed..
Recreate the bootable flash drive and do it again. Maybe use app Install Disk Creator to make the flash drive.
Have you erased the internal drive? You have to do that. Be sure you have backups.
Lo_Ré wrote:
Yes. it had. I really can't explain.
FWIW, if one iMac had Big Sur installed and was upgraded to Monterey before you received it, then it should be possible to downgrade it. If the second iMac had Monterey originally installed, then as explained, it cannot be downgraded.
Q - " I'm trying to downgrade from Monterey to BigSur on an iMac with T2."
A - If this computer can New and Installed with Monterey macOS 12 - this downgrade can not be done - period.
The Apple " Licence of Use" prohibits installing an Older Version of macOS than the one it came. with pre-installed.
There is the answer - Monterey installed as a New Computer can not be downgraded/
Even if using a Bootable Installer of Big Sur or another means period.
The Apple " Licence of Use" prohibits installing an Older Version of macOS than the one it came with pre-installed.
Only wish the answer was not so - but it is what it is.
You are welcome and thank you too.
Do come back to the Apple Support Communities ( ASC ) in the future, if / or when additional questions may arise
Thank you! I've tried the flash drive on another Mac, and it works.
I've erased twice the internal drive.
Thank you for the answer, but in my office we've bought two identical iMac. The first one has been downgraded the same way :(
And the Second computer ( problematic ) had Monterey installed when it was purchased ?
Yes. it had. I really can't explain.
ok. thank you for your time and your precious answers.
Yes, it would be great.
I will of course!
Thanks!
Not able to downgrade to previous macOS
