Reverting from Tahoe 26.1 to Sequoia on M3 Macbook Air

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Level 1

4 points

Reverting from Tahoe 26.1 to Sequoia on M3 Macbook Air

I've just upgraded my M3 Macbook Air to Tahoe 26.1. This has caused software using OpenGL to fail. I'd like to undo the install, and revert to Sequoia. I have a backup made on Sequoia via Time Machine.

I've read online that the way to do this is to start by making a bootable USB disk with Sequoia on it, but the online instructions to do that don't work: Software Update won't let me download the Sequoia installer.

How do I undo the Tahoe install?

[Re-Titled by Moderator]

Original Title: Undo Tahoe install

MacBook Air 13″, macOS 26.1

Posted on Nov 9, 2025 2:04 AM

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Answer 1

Owl-53

Level 10

102,193 points

Nov 9, 2025 2:56 AM in response to djm121

What is the users tolerance for " Risk " ?

1 - Is this your Only computer and you would not be able to live without it for a fews days if the downgrade procedure goes wrong ?

2 - Does the user have access to another Apple computer, that currently is running macOS 15 / 26 , that could be used to Revive or Restore the computer Firmware ?

3 - IMPORTANT >> Understand that once the computer has upGraded to macOS 26 Tahoe. there is a strong probability there was a Firmware upGraded that was applied to the computer

Downgrading back to an older version of macOS, say Sequoia

It runs the Risk that doing the downgrade, there could be issues with the existing Firmware also being downgraded.

4 - Does the user have at least 2 - no - make that 3 backups from a time before the computer was upGraded to macOS 26 Tahoe ?

Have a 3-2-1 Rescue Plan in place and always current

3 Backups using 2 methods and 1 off site incase of natural disaster or un-natural disaster.

Each of the above should be done to a Dedicated Single Purposed External Drive

Below link is intended to augment what TM Backup does

https://bombich.com

If the owner of this computer should answer NO to any of the above questions

Then downgrading the computer Is Not Recommended

______________________________________________

On an Apple Silicon Mac, downgrading to an older macOS version requires a full erase of your computer's internal drive.

You cannot simply install an older version over a newer one.

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Answer 2

djm121 Author

Level 1

4 points

Nov 9, 2025 9:20 AM in response to djm121

The reversion appears to have worked. There are minor glitches like those you get whenever you move to a new laptop, but generally things seem fine.

For the benefit of anyone else trying this, here's the advice:

Before upgrading to Tahoe, do a Time Machine backup in Sequoia.
After upgrading and deciding you want to go back, find some online instructions. There are lots of sources, and they all follow similar patterns: Make an external disk bootable to Sequoia, wipe your main laptop disk (that's why you need a backup!), reinstall Sequoia to the main disk, restore from your backup.
I used the commandline version of the instructions. These use two main commands in terminal:

softwareupdate --fetch-full-installer --full-installer-version 15.7.2

followed by running the installer you just downloaded. You need `sudo` for the second step, something like

sudo /Applications/Install\ macOS\ Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/USBDrive

where `USBDrive` is the volume name for your external drive.

I received an error message when downloading the installer, because it looks like it tried to run it right away to install on the main drive. Apparently you can ignore that message, and run again specifying the external volume.
When you do the reinstall, you'll need your Apple password to activate the OS, and you may need encryption passwords when you restore from your backup. Make sure you know those!
I've left out lots of details: read a few of those online instruction sets before you start anything.

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Answer 3

djm121 Author

Level 1

4 points

Nov 9, 2025 2:42 AM in response to djm121

I've now got the download happening. I think the issue was that I had an item in Applications that was a failed download of the installer, and it was blocking the new download. I removed that, and am now attempting the download again.

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Answer 4

djm121 Author

Level 1

4 points

Nov 9, 2025 11:25 AM in response to Owl-53

Thanks for the warnings. I agree that backups are essential. I probably wouldn't have attempted the reversion if I had made the backup in Tahoe: you need to remember to do it *before* the upgrade.

I think Apple should make this kind of thing easier. Their documentation for doing it is poor, but luckily plenty of bloggers describe it better.

Their support for open source projects like XQuartz also leaves a lot to be desired. If Tahoe's X11 support doesn't improve in the next couple of years (i.e. before Sequoia is unsupported), I'll probably switch to some Linux version rather than upgrading to Tahoe.

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