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Downgrade from Big Sur to Mojave

Hi everyone, I have the necessity to downgrade my Macbook Air M1 from Big Sur to Mojave or High Sierra, is it possible?

I ask this as I have Adobe CS6 and it's not possible to install it on Big Sur, so from Adobe support suggest this solution.

Are there any possible issue I may fall into?


Thanks everyone for the help.

MacBook Air (2020 or later)

Posted on Aug 19, 2021 12:00 AM

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Posted on Aug 19, 2021 1:35 AM

Not possible. The Apple Silicon M1 came preinstalled with Big Sur and can not be downgraded to any version of macOS older than Big Sur.


Aside - even if one attempts - Catalina , Mojave or High Sierra could not run the the new Apple Silicon M1 based on the ARMS chip instructions. Catalina , Mojave and High Sierra is written for Intel CPU Only instructions.

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Question marked as Top-ranking reply

Aug 19, 2021 1:35 AM in response to Artosi_A

Not possible. The Apple Silicon M1 came preinstalled with Big Sur and can not be downgraded to any version of macOS older than Big Sur.


Aside - even if one attempts - Catalina , Mojave or High Sierra could not run the the new Apple Silicon M1 based on the ARMS chip instructions. Catalina , Mojave and High Sierra is written for Intel CPU Only instructions.

Aug 19, 2021 12:25 AM in response to Artosi_A

Edit: oh, you have M1 Mac which is Big Sur or later only.


Download the Mojave full installer with Safari, backup, make a bootable Mojave USB flash installer, boot it, reveal and erase the whole internal device (not just volumes under it) as APFS (GUID) and cleanly install Mojave to the internal disk, restore from the backup.


https://support.apple.com/en-us/HT211683


https://support.apple.com/en-us/HT201372


Oh, and Photoshop CS6 installer needs a workaround to install on Mojave and its updater does no install all little updates. But basically it works OK in Mojave.


A SSD is highly recommended for APFS because it is slow on HDD. Or install High Sierra and use MacOS Extended (GUID) on a spinning HDD disk.

Downgrade from Big Sur to Mojave

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