How to Run Two Versions of macOS on the Same Mac

So, you want to try out the latest macOS beta but don’t want to lose the stability of the current system? You’re not alone. We also like to get an early look at the latest software, but we‘re also very aware that beta software is often buggy and that the majority of apps used on a daily basis aren’t yet compatible with it, and so overwriting the stable macOS currently being used could potentially cause the unwelcome deaths of millions of neurons.

How to install macOS Beta on your Mac

Mac users with startup disk formatted as APFS will need to follow some preparatory tasks to get the system ready:

1. 1. Launch Disk Utility and select your startup disk (usually Macintosh HD). Remember, the following steps only apply to users running macOS 10.3 High Sierra or later.
   2. Click on the Add Volume button (“+”) to add another volume to your disk.
   3. Name the newly created volume Mojave, or whatever name you prefer.
   4. Choose APFS as the volume’s format. At this point, you can set a minimum and maximum storage limit for the volume by clicking on the Size Options and entering the desired values.
   5. Finalize it by clicking the Add button.

Install macOS Mojave

1. Before getting access to the beta version of macOS Mojave, you will need to sign up for the public beta program on beta.apple.com.
2. Sign in with your Apple ID and enrol your device onto the program.
3. Download the Public Beta Access Utility and install the package file onto your Mac. A second app, Feedback Assistant, will also appear, but this can be ignored it at this point.
4. Enter the Mac App Store and you’ll see the macOS Mojave public beta downloader. If not, go to the Updates section and locate it there.
   1. Click to download the Mojave installer. Since you’ll download close to 6GBs of data at this point, it will take some time depending on your internet connection.
   2. When the download has finished, it will automatically launch the installer. Click “Continue”.
   3. Agree to the terms and click the “Show All Disks” button to reveal your newly created APFS volume. Note: if you don’t do this, you’ll overwrite the stable operating system and you’ll have lost the option to dual boot.
   4. Select the Mojave partition and click install.
   5. Follow the on-screen instructions and wait for the installer to finish its job.
   6. Enjoy macOS Mojave.

   Next time you start your computer it will automatically boot into macOS Mojave, which is fine if you only want to use the latest operating system. However, if your daily tasks are centered around the ‘old’ and stable operating system, then you’ll need to do a simple trick to make sure that the Mac will only boot into macOS Mojave when you want it to.

   1. Launch System Preferences.
   2. Open the Startup Disk pane. You’ll see at least two systems listed there: the old one (macOS 10.13.x) and the new one (macOS Mojave 10.14).
   3. Click on the lock icon to make changes and enter the admin password when prompted.
   4. Select macOS 10.13.x as the default operating system.
   5. Close the lock to prevent further changes.

   Install a second macOS on HFS+ formatted drive

   Those who skipped formatting their drive to APFS can still install the public beta macOS Mojave (or any later OS). The only change in the preparation stage is to add a partition instead of a new volume and format it as Mac OS Extended (Journaled).

   How to boot into macOS Mojave

   Now that you have everything set up to dual boot and the time to play around with Apple’s latest operating system, all you need to do is start the Mac and press the Option key until the Startup Manager appears. Here you’ll see the two macOS versions (the two volumes), so select Mojave as shown in the image above. And that’s it. Enjoy macOS Mojave and don’t forget to send Apple your feedback on how the operating system behaves on your machine.