How To

How to Clean Install macOS Catalina Final

Written by John


After every Apple World Wide Developer Conference, ardent Mac connoisseurs can always expect something to smile about. I mean, it is usually a statement that something new is about or going to be launched which more often than not enhances the user experience of Apple devices. After the latest conference in July, the tune was no different. Besides announcing upgrades to several devices, Apple released macOS 10.5 Catalina, which is the latest operating system under its brand. On the 7th of October 2019, Catalina 10.15 Final was released, and enthusiasts all over the world have started to enjoy the many benefits it has to offer.

If you have not yet joined the lot, but are looking for a way to clean install macOS Catalina with a USB, you are on the right path and at the right place. And there is nothing complicated about it. With just three steps, you should be able to make a clean install from your USB as long as your device is supported. But how? Well, that’s where we come in. In this post, you are going to learn all there is to know about installing macOS Catalina Final with a USB installer. But first…

Make sure that your Mac is compatible
To avoid wasting time and resources, first make sure that your Mac has the hardware requirements to install Catalina 10.15. It will be an exercise in futility to attempt installing the OS if your Mac is not compatible. Some of the compatible devices include:

  • MacBook Air 2012 and later
  • MacBook 2015 and later
  • iMac Pro 2017 and later
  • Mac Mini 2012 and later
  • Mac Pro 2013 and later
  • MacBook Pro 2012 and later
  • iMac 2012 and late

Backup your Mac
As you already know, installing any OS completely erases your startup drive. Therefore, if you would not like to lose your current installation, make sure that you have backed up your device before proceeding with any of these steps. This can be done with a cloning or back up app to External Hard Drive. Once you are comfortable that you’ve created backups for everything you will need later, you can comfortably proceed.

How to Clean install macOS Catalina

Step 1: Downloading macOS 10.15 Catalina Final

This is perhaps the most straightforward part of this process. I mean, it as easy as visiting the Mac App Store and downloading the OS like you would have downloaded any other application. But so that you can be sure, here is the process.

  1. On your Mac, download macOS Catalina Final with this link.
  2. Then click on “Get” button.
  3. The files will then be downloaded to your computer automatically.

Step 2: Now We need to Create a USB Installer for the new macOS Catalina 10.15

Since Catalina 10.15 currently available as a Final version, it is highly recommended that you clean install it by creating a dual boot system when running it. That’s why using a USB installer is always the best option. And here’s how to create one:

You’re now going to want to rename your inserted USB flash drive as ‘USB’. Once you’ve done that the next step is to enter the following line of code in the command line of your terminal:

  1. Open “Terminal” by going to “Applications” then selecting “Utilities.”
  2. Then key in the following command:
    sudo /Applications/Install\ macOS\ Catalina.app/Contents/Resources/createinstallmedia --volume /Volumes/USB --nointeraction

Once you’ve done that you’ll take note that the Terminal application now needs your password an admin to authenticate the command above. Sudo requires admin access. Finally, once you’ve done all the above the USB installer drive should have been created, and you should now be able to install macOS Catalina through your USB drive installer.

Create a macOS Catalina Installer with Terminal

Step 3: Install new macOS Catalina

Now that we’ve created our partition it is now time to install macOS Catalina on this newly formed partition and so to do this you’ll need to follow these steps:

  • First and foremost ensure there is a connection present between the USB Installer and your Mac.
  • Restart your Mac. Upon it rebooting straight away hold down your ‘Option’ key until a boot menu appears.
Boot to macOS Catalina USB Installer

  • Once you see this boot menu, go ahead and highlight Install macOS Catalina and press Enter.
  • "macOS utilities" will then appear on the screen. Go ahead and select "Disk Utility".
  • After "Disk Utility" launches, select the "Erase tab" then choose your startup volume. This could be labeled as Macintosh HD.
  • Name your startup disk and choose a format and choose APFS, if it has a standard drive, you can select any format.
  • Click on “Apply” and once the disk has been completely erased, return to the macOS utility screen.
Create a New Partition for macOS Catalina

Once there, click on “Install macOS Catalina” click on “Continue” then select the destination as the disk you have already formatted, and macOS will then start installing.

Clean Install macOS Catalina on new partition

Once the installation is done, your Mac is going to restart, and all you have to do to complete the process is set up a user account. After you are done with the setup, dismount the USB drive. You can then restore the files you had previously backed up and forget to keep it safe since you could be needing it again.

Done! Keep Your Mac Clean after install to macOS Catalina

Over time, your Mac accumulates junk files which ultimately end up compromising its performance. Fortunately, Clean My Mac is built with tools and features that access the state of your drives and make the most rational decisions. For instance, it can detect extremely huge files which makes it easy for you to get rid of them with just a few clicks. Cleaning your drives will provide more space which you can use to store important files at the same time, improving the overall performance of your Mac.

Clean up both your System and App Junk

Bottom Line

Besides being acquainted with the latest developments on the Apple platform, there are several other reasons why you would like to clean install macOS Catalina 10.15. Perhaps, the most important of all is experiencing the feel, the look, and user-friendliness that new features offer. And with the latest version of Catalina 10.15 having been released, nothing can stop you now.

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