Installing Catalina without risking your job, current your install or your sanity

It can be hair raising trying to install a new operating system on your Mac, particularly when it is a beta version. This guide has you covered!


macOS: Apple’s operating systems used on Mac machines

Catalina: macOS 10.15, Apple’s latest version of macOS

APFS: Apple’s file system introduced with macOS High Sierra

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One of the following macs:

  • MacBook (early 2015 or later)
  • MacBook Air (mid 2012 or later)
  • MacBook Pro (mid 2012 or later)
  • Mac mini (late 2012 or later)
  • iMac (late 2012 or later)
  • iMac Pro (all models)
  • Mac Pro (late 2013 or later)

And a developer account, and to follow this guide your disk should be formatted as APFS (which it most likely is, if you are using High Sierra. In any case Disk Utility will tell you the file system you are on).

The rub

Usually you install a new version of macOS over your previous version. However, Catalina is the first version of macOS that stops you running 32bit versions of applications that you have. In other words, when you upgrade to Catalina your workflow may be significantly impacted by the change and in my case I wanted to delay this change as much as possible.

The preparation

Disk Utility allows you to set up a new volume on your existing disk, and better still allocated disk space on demand. This means that providing you have space on your disk, it will dynamically adjust space for you, while not risking your existing data!:

  • Find Disk Utility on your Mac (the easiest way is command-space and type Disk Utility)
  • Make sure you main internal drive is selected, and that it is formatted as APFS.
  • At the top of the screen add a new volume
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  • Name your drive (Catalina is a good name)
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After you have done this you should remember to write down your wifi password — you’ll need it in your Catalina installation.

The installation

The only thing to be aware of as you install Catalina is to remember to install it to your new volume that you have set up.

  • Go to
  • Select develop at the top of the screen
  • Select downloads
  • Click on “Install Profile” next to macOS Catalina 10.15 beta (at the time of writing)
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  • Click on “Install Profile” next to macOS Catalina 10.15 beta (at the time of writing)
  • Open the file that is downloaded, installing the profile
  • You can now update your Mac, and this is what you want to do (just make sure that you choose the new disk that you have selected at the appropriate juncture).

The mac will go through the same nerve wracking process of restarts, before booting into Catalina as a fresh install which you will setup as usual.

If you take a look in Disk Utility at your new install it is there — but your original install is still there (mine is called Macintosh HD, as below)

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Switching back

This can be done by holding down the option key when you startup the Mac!


Here is Apple’s guide to setting up your partitions:

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