Mac mini M4: macOS downgrade & external keyboard for startup

vnx273 wrote:

Hello everyone,

I’m currently using a Mac mini M4 running macOS 26, and I would like to downgrade it to macOS Sequoia 15.2.

Just curious why you want to go through the hassle to downgrade the OS? Especially to 15.2 when the latest update for Sequoia is 15.7.3.

If you are having specific issues with Tahoe, then explaining those issues and posting a complete EtreCheck report will allow us to assist you with any Tahoe related issues.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

I’d like to ask:

Is the downgrade process on a Mac mini M4 the same as on a MacBook (for example, using Recovery Mode or a bootable installer)?

With an M-series Mac, you need to create & use a bootable macOS USB installer to downgrade the OS.

Create a bootable installer for macOS - Apple Support

When booting into Recovery or selecting a startup disk on Mac mini M4, do I need to use an external keyboard, similar to how it’s required on some MacBook models?

An external keyboard is only needed if you are using a Desktop Mac, or your laptop's built-in keyboard is bad.

Otherwise using an external keyboard is up to you.

Any guidance or shared experience would be greatly appreciated.

Thank you very much!

Here is an Apple article for reinstalling macOS...you will need to use Disk Utility to erase the Volume Group since you want to downgrade the OS.

How to start up from macOS Recovery on an M-series Mac - Apple Support

When downgrading the OS you will need to restore from a backup made prior to the upgrade to Tahoe. You do not want to restore any Apple libraries from Tahoe to an earlier OS since those libraries may no longer be compatible with the older OS. For any other data, you will need to manually recover them to the downgraded OS from the backup.

Downgrading an OS can be a huge pain depending on how much your data has changed since you've done the upgrade. It is usually best to resolve any issues with the current OS.

If you don't have any backups, then you are in for a world of pain to downgrade the OS and you will definitely want to make sure you have at least two different good backups before attempting the downgrade.

Owl-53 wrote:

Firmware Compatibility and Secure Enclave Risks

Be aware that upgrading to macOS 26 (Tahoe) likely includes a firmware update affecting the logic board and Secure Enclave Processor (SEP).

Downgrading to an earlier version (e.g., Sequoia) may or may not introduce firmware mismatch issues, leading to instability or loss of functionality.

The only thing I've noticed is when people dual boot macOS on an M-series Mac.

When booting into the other OS, the system may actually add an extra mini boot to load up the other firmware like system files which requires a reboot before the other OS will actually boot. This does make troubleshooting more difficult....especially for boot issues.

This does affect which style of Apple Diagnostics are loaded (traditional style which run automatically when selected, or the new style where you can choose from several tests to run). If you dual boot Sequoia & Tahoe on an M-series Mac, then the last version of macOS which was booted will determine which version of Apple Diagnostic will be used. I believe the same thing is likely to apply to Recovery Mode, but I haven't tested it.

Otherwise I don't think there is any problem regarding firmware especially if the person only has one OS installed on the Mac.

Firmware Compatibility and Secure Enclave Risks

Be aware that upgrading to macOS 26 (Tahoe) likely includes a firmware update affecting the logic board and Secure Enclave Processor (SEP).

Downgrading to an earlier version (e.g., Sequoia) may or may not introduce firmware mismatch issues, leading to instability or loss of functionality.

vnx273 wrote:

Thank you for the reply!

I currently have two Mac mini M4 machines — one is running macOS Sequoia 15.2 and the other is on macOS Tahoe 26.

Make sure you have updated Tahoe to 26.2 since that update did help stabilize Tahoe in regards to releasing memory & storage so apps don't get the "out of memory" errors.

Based on my experience so far, 15.2 feels more stable for my daily workflow,

If you can provide any examples, perhaps the forum contributors will be able to offer some guidance. You may want to run the third party app EtreCheck and post the complete report here so we can examine it for possible clues.

How to use the Add Text Feature When Posting an EtreCheck Report - Apple Community

You should make sure all of your third party apps are completely up to date running their most recent versions, and that those versions are fully compatible with Tahoe.

so I’d like both machines to run the same macOS version for consistency and stability.

That’s the main reason I’m considering downgrading, rather than troubleshooting a specific issue on Tahoe at the moment.

I appreciate your input and guidance — thank you!

Your choice of course, but I think it would be better to try & resolve any perceived Tahoe issues first since you have one system with it already. If the new Tahoe visuals are not the problem, then the rest of Tahoe should not be too much of an issue with 26.2. If Tahoe broke some part of your workflow, then maybe a contributor will have some other options for you. All future versions of macOS will just be more changes to Tahoe, so it might be worthwhile to figure out the issues now while one system is already running it. Depending on the apps you use and the online services you require.....sooner or later you will likely need to upgrade macOS to something newer.

Of course if you have some app or external hardware device which has compatibility issues with Tahoe, then perhaps you may need to downgrade if the developer/manufacturer if a fix is not due for a while.

You know your system & workloads best and how much any issues & troubleshooting, or downgrading macOS may impact things at this point.

Give up the idea of Downgrading to Sequoia 15.2 >> macOS 15.2 ( 24C101 )

That version was released Dec 11, 2024

The Oldest Version of Sequoia available from Apple is as per below

Finding available software

Software Update found the following full installers:

* Title: macOS Tahoe, Version: 26.2, Size: 16975578KiB, Build: 25C56, Deferred: NO

* Title: macOS Tahoe, Version: 26.1, Size: 16890687KiB, Build: 25B78, Deferred: NO

* Title: macOS Sequoia, Version: 15.7.3, Size: 15286709KiB, Build: 24G419, Deferred: NO

* Title: macOS Sequoia, Version: 15.7.2, Size: 15285166KiB, Build: 24G325, Deferred: NO

Thanks for sharing this!

I’ll trust your expertise and knowledge of hardware to handle this.

As long as the person who posted knows about the remote possibility of a firmware issue and takes all the necessary precautions beforehand, I’m good with this. 

It is a pleasure working with you