How to downgrade from Tahoe

Apple Silicon computer no doubt ?

Not for the " Faint of Heart "

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. 

Before you begin, you must first create a complete backup of all your data. 

Step 1: Back up your Mac 

This is the most critical step. Downgrading will erase your Mac's internal drive, so you must back up your files and settings beforehand. 

Time Machine (recommended): Use Apple's built-in Time Machine to create a full backup on an external storage drive.

➡️ Manual copy: Alternatively, you can manually copy all your essential files to an external hard drive ⬅️

Step 2: Create a bootable installer for macOS 15 

To install the older operating system, you will need a bootable USB installer. 

1. Download the installer: On a Mac compatible with macOS 15, download the "Install macOS Sequoia" app from the Mac App Store.
2. Use Terminal: Connect a USB flash drive with at least 15GB of free space. Open the Terminal app (in Applications/Utilities) and use the createinstallmedia command to turn the USB drive into a bootable installer. The command for macOS 15 Sequoia is:
3. sudo /Applications/Install\ macOS\ Sequoia.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume
4. (Replace MyVolume with the name of your USB drive)

Step 3: Erase your Mac's internal drive 

1. Shut down your Mac: Turn off your computer completely.
2. Enter Recovery Mode: Press and hold the power button until you see the "Loading startup options" screen.
3. Choose Options: Click the Options icon, then click Continue.
4. Open Disk Utility: From the Recovery screen, select Disk Utility and click Continue.
5. Erase the drive: In the sidebar, select your Mac's internal drive, usually named "Macintosh HD." Click the Erase button and enter a new name for the volume. Ensure the format is set to APFS, then click Erase Volume Group. 

Step 4: Install macOS 15 from the bootable installer 

1. Quit Disk Utility: After the erase is complete, close Disk Utility to return to the Recovery menu.
2. Select the installer: Click the Install macOS Sequoia option. You may need to connect to Wi-Fi at this point.
3. Choose the drive: Follow the on-screen instructions and select the internal drive you just erased as the destination for the installation.
4. Complete the installation: Wait for the installation to finish. Your Mac will restart several times. 

Step 5: Restore your data 

1.  Restore manually: If you copied your files manually, you can skip Migration Assistant and drag your backed-up files back into their respective folders. 

Important considerations 

• Data loss: Any new files or changes made on macOS 26 since your last backup will be permanently lost during the downgrade.
• Application compatibility: Some apps that were updated for macOS 26 may not work correctly on macOS 15.
• Hardware compatibility: Your Mac must be compatible with macOS 15. A Mac that shipped with macOS 26 cannot be downgraded to a version it never supported.

• Firmware: Downgrading to a much older macOS version may also involve a firmware downgrade, which adds risk. The Apple Configurator tool can be used for more robust downgrades.

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How do downgrade from tahoe? - Apple Community

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downgrade from Tahoe - Google-

An aside form your main issue

Also started on a PPC Powerbook with OSX 10.4 Tiger and moved though every single version since then to Now Tahoe 26

Adaption on my part were and are needed to keep ones sanity

Since some time, Apple has decided ( no judgements here ) to semi merge some of the UIs from the iOS into macOS

This is a Cross-Platform Cohesiveness

Liquid Glass extends to all of Apple's operating systems, including iOS 26, iPadOS 26 macOS 26, tvOS 26, watchOS 26, and of course, visionOS 26, which is the OS that inspired the overhaul. 

With the same design available across all of Apple's operating systems, everything feels more cohesive, which was one of Apple's main goals with Liquid Glass. 

There seems to be no way to escape this

Just saying

Ralph Stokes wrote:

For now, I'll remain hopeful that they'll undo the damage with the next OS though - and hopefully rush it through. Anything is better than this. I'm just really glad I only updated my laptop and not my primary studio machine!

Hum

You may consider following the Apple WWDC, scheduled sometime early June of this year visa vie macOS 27, iOS 27 etc

Unless Apple does a " Re-Think " on their Cross-Platform Cohesiveness

I might expect, the lines between macOS and iOS may become even more " Blurred "

You are welcome for the detailed instructions.

Not that this will really make this matter any better

🦉-53

Ralph Stokes wrote:

I'm not opposed to Cross-platform cohesiveness, but it needs to be done properly - not like this.

There is very little about Tahoe that makes it feel cohesive with the experience I have on my iPhone in my opinion.

No complaint about the concept in general but I would expect much better implementation than this from Apple.

Use the Product Feedback - and make it known to Apple regarding this matter

I am not demeaning or pushing off what you are observing

Like I say to some

We Own our Apple Devices, on this we agree

We do not Own the Operating Systems

We only Lease it from Apple

I think we know where is may leed

Ralph Stokes wrote:

We Own our Apple Devices, on this we agree

We do not Own the Operating Systems

An interesting point, because the only reason I own an apple computer at all is so that I can run the operating system!

That is fair—and honestly kind of ironic, right?

People buy into Apple largely because of the operating system and ecosystem experience, not just the hardware.

So when something like Tahoe feels out of sync, it stands out more than it would elsewhere.

I guess that is the trade-off with Apple’s model: they control the OS to keep things consistent, but that also means users are relying on them to get that experience right every time.

When it misses, there is not much you can do except give feedback and hope it improves.

I do hear would you are saying 👍

My usual response is . . .

Apple does what Apple believes is best for Apple

They have worked this way for decades and I do not see this changing any time soon

To be balanced

What is currently appearing in the Development stage, , does not always make it into the Final Publicly Released version

We can only hope for the best

https://www.macrumors.com/roundup/macos-27/

Ralph Stokes wrote:

And thanks for the detailed response/instructions. Gonna be a bit of a faff and require a new drive but has to be done!

👍

Two month on.

We now have some idea as to what macOS 27 Golden State may look like in regards to Liquid Glass

Apple added a full Liquid Glass slider under System Settings