How can I downgrade from the macOS Sierra beta on my Mac? Can I revert back to OS X El Capitan? How do I remove macOS Sierra from my Mac?
Before we explain exactly what to do, let's first outline what you can't do:
You can't boot your Mac into Recovery mode and revert to El Capitan because this method can only be used for reinstalling the system that's currently on the Mac, which in this case is El Capitan.
You can't run the El Capitan installer within macOS Sierra, because the Mac always wants to have the latest version of macOS.
What you can do is completely erase macOS Sierra, re-install El Capitan from scratch and then restore your original pre-Sierra data from a Time Machine back up you made before you downloaded the Sierra beta (like Apple suggests).
Before you start, make a backup of any new files you'd recently added in Sierra and store them on a hard drive (not the one you are about to use to create the installer though). Don't make a Time Machine back up either - the only Time Machine back up should be your back up of El Capitan before you updated to macOS Sierra. [Here's our how to install El Capitan article, in which we recommend you make a backup first!]
Disclaimer: We haven't tested this method with the macOS Sierra public beta just yet, but based on past downgrade experiences with the likes of El Capitan, Yosemite and even Mountain Lion, we're confident that this is how it's done.
How to downgrade from macOS Sierra to El Capitan: Create an El Capitan install drive
Before you remove macOS Sierra from your Mac, create an El Capitan installation drive. Here's how:
- First, download the OS X El Capitan installer from the App Store. It should be in your Purchases section.
- Click on the Download button.
- After the installer downloads it will auto-launch, and inform you that you're running a newer version of OS X. You’ll need to quit the installer at this point as you won’t be able to install it on top of macOS Sierra.
At this stage you need to create a bootable installer on a separate hard drive. You'll need at least 8GB of storage available on an external drive, that is formatted with a GUID Partition Table, on which to put the installer. It is important (for this tutorial) to leave the default name, which is Untitled.
It's not just a case of copying the download file over, though: you should make a bootable OS X El Capitan install drive. Using a bootable installer drive is necessary because you need to erase the drive on your Mac (including all traces of Sierra) before installing El Capitan. This way you can do a clean install of the OS and restore any data you have in your backup.
There are a few ways in which you can create that installer. You can use the installer's built-in createinstallmedia tool; use Disk Utility; or perform the Disk Utility procedure using Terminal.
The createinstallmedia method is the simplest, and doesn't require you to be competent in Terminal - even the Disk Utility method requires a couple Terminal commands. However, you will need to open up Terminal to use it.
Here's what you need to do to use createinstallmedia:
- Connect your Mac to the properly formatted 8GB hard drive. Rename the drive Untitled. (Make sure there is no data on the drive as it is going to be erased!)
- Make sure the El Capitan installer (Install OS X El Capitan.app) is in the correct location in the main Applications folder.
- Launch Terminal and paste in this command:
- sudo /Applications/Install\ OS\ X\ El Capitan.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ OS\ X\ El Capitan.app --nointeraction
- Enter your admin password when required
You will see the progress in the Terminal window, which could take up to half an hour. Eventually you will see the words: Copy Complete. Done.
You now have your bootable OS X El Capitan install drive ready to recover your Mac from the grip of macOS Sierra.
How to downgrade from macOS Sierra to El Capitan: Remove macOS Sierra from your Mac
Now you have your Bootable Installer, and have backed up any new files, you can safely erase the Sierra volume. You have to erase it before you can install El Capitan again.
Here is how to boot from that Bootable Installer and wipe Sierra from your Mac:
- Shut down your Mac and connect the drive to your Mac. Hold down the Option/Alt key at startup and when you see the drive icon labeled Install OS X El Capitan, click on the arrow below it to start the install.
- Select Disk Utility when the OS X Utilities window appears.
- When the Disk Utility app launches, choose your Mac’s hard drive and click on the Erase tab. Name your hard drive and select one of the OS X Extended formats.
- Click Erase and wipe your hard drive.
How to downgrade from macOS Sierra to El Capitan: Install El Capitan from a Bootable Installer
Once your Mac has been wiped you can install El Capitan from your Bootable Installer. Here’s how:
- Quit Disk Utility.
- Select Install OS X, click Continue, and follow the installation process.
- Assuming you made that back up before you installed Sierra, you can now connect to your Time Machine drive and run Migration Assistant to restore all your files from the back up.
- Finally any additional data you had created since installing Sierra, and had backed up (not using Time Machine) can be restored.