Downgrading?

[Astrohunter]

Hi,

I want to downgrade to Sequioa, silly me shouldn't install dev beta, but oh well...

I've created a USB installer, but I've heard that after formatting the drive I won't be able to select my drive to install it to, because of some security stuff, and mismatch of firmware.

Is there any workaround?

I've heard also about DFU method, but would it work if the second Mac that I would have to borrow is Intel based?

Thanks

 

[gilby101]

For Apple silicon need to use DFU mode. After base install use Migration Assistant to recover the rest using a TM backup made with Sequoia. Details, requirements and instructions for DFU are here https://support.apple.com/en-us/108900

 

[Solenoid289]

I just downgraded from macOS Tahoe to Sequoia (Mac Studio M1 Max).
As long as your Mac is connected to the internet, the process is actually quite simple.

• Boot into macOS Recovery.
• Open Disk Utility.
• Erase the entire “Macintosh HD,” then reboot.
• Select “Reinstall macOS Sequoia.”

After installation, you can either restore from a Time Machine backup or set it up as a new Mac.

Note: If your Time Machine backup was created while running Tahoe, you won’t be able to restore it after downgrading due to version incompatibility.

 

[Astrohunter]

I just downgraded from macOS Tahoe to Sequoia (Mac Studio M1 Max).
As long as your Mac is connected to the internet, the process is actually quite simple.

• Boot into macOS Recovery.
• Open Disk Utility from the menu bar.
• Erase the entire “Macintosh HD,” then reboot.
• Select “Reinstall macOS Sequoia.”

After installation, you can either restore from a Time Machine backup or set it up as a new Mac.

Note: If your Time Machine backup was created while running Tahoe, you won’t be able to restore it after downgrading due to version incompatibility.

I'm surprised it worked for you, because if you install beta the firmware should change.
A lot of people reported that after erasing the disk things went south, or that they couldn't erase it, or select it to install. (Don't remember exactly)

I ended up borrowing a Macbook, connected it to my Mini, and used that Apple app (forgot the name) on the Macbook which lets you drag&drop the firmware/OS.

 

[Solenoid289]

I'm surprised it worked for you, because if you install beta the firmware should change.
A lot of people reported that after erasing the disk things went south, or that they couldn't erase it, or select it to install. (Don't remember exactly)

I ended up borrowing a Macbook, connected it to my Mini, and used that Apple app (forgot the name) on the Macbook which lets you drag&drop the firmware/OS.

I’m not aware of the issues many people have reported, but in my case, downgrading from macOS Tahoe to Sequoia was quite straightforward.

In fact, my Mac Studio was repaired under AppleCare in April 2025 due to corrupted firmware. Apple’s repair engineer rewrote the firmware, and the machine was returned to me with the latest version of macOS Sequoia (15.4) installed at that time.
It’s possible that the engineer quietly fixed an underlying firmware flaw during the repair, but I can’t say for sure.