macOS Catalina was the newest operating system by Apple until macOS Big Sur succeeded it in 2020. If your Mac still runs Mojave or an even older macOS version, you’ll be amazed by all the new features and improvements in Catalina. So here’s how to upgrade to macOS Catalina.

First, clear out the junk

When you do a regular upgrade, the installer replaces some files on your Mac with others but leaves most untouched. That means that all the system junk your Mac has accumulated over the years stays there. And as you upgrade year after year, you accumulate more and more. As you can imagine, upgrading your operating system on a junk-filled Mac is rather like putting one layer of wallpaper on top of another — eventually, you have to scrape it off and start again. 

Likewise, it’s always a good idea to clear out the clutter before you upgrade. My recommendation after years of experience upgrading Macs is that you use CleanMyMac X. It’s very quick and easy to use and will help you get rid of clutter, making your Mac run more smoothly and freeing up tens of gigabytes of disk space. You can either let it decide what to remove or go through its scan results yourself and decide what to trash and what to keep.

CleanMyMac - System junk scan complete

Then, backup your Mac

As you will see below, there are a couple of different ways you can upgrade to Catalina, but before you decide, and certainly before you upgrade, you should make a full backup of your current Mac setup. Upgrading one OS on top of another carries very few risks, but they are not non-existent, so be safe now rather than sorry later. If you use Time Machine, you can make a backup with that. But the best idea is to make a complete bootable clone of your current startup disk on an external drive.

To clean install or not to clean install

Remember I said you had a couple of options for upgrading? Here they are:

  1. Regular install
  2. Clean install

A regular install places Catalina files on your startup disk over the top of whatever OS you’re currently running. It doesn’t overwrite anything else. So all your applications, documents, settings, photos, movies, and music stay where they are. Unfortunately, all the junk files your Mac has accumulated also remain there. This option is quicker in the short term, but your Mac won’t run as smoothly in the long term. If you choose this option, I’d definitely recommend you use CleanMyMac X to clear out the clutter before you upgrade.

A clean install erases your startup disk completely and then installs macOS Catalina on a completely clean disk. It takes longer, but in the long run, your Mac will run more quickly and smoothly. You will have to clone your startup disk before you start and then spend time reinstalling applications and setting them up afterward, however. 

How to do a regular install of macOS Catalina

  1. Check that your Mac can run Catalina. Here’s the list of compatible Macs:

MacBook 2015 and later

MacBook Air 2012 and later

MacBook Pro 2012 and later

iMac 2012 and later

iMac Pro 2017 and later

Mac Pro 2013 and later

2. Make sure you’re connected to the internet and have a stable connection. If you’re using a MacBook, MacBook Air, or MacBook Pro, plug it into mains power.

3. Open the App Store app on your Mac and search for macOS Catalina.

4. When you find it, click Get.

5. Wait for Catalina to download, and when it’s ready to install, click Continue. Type in your admin username and password if necessary.

6. Wait for Catalina to install. Your Mac will restart several times, and it may take a while, so be patient! If you are using a laptop, don’t close the lid.

7. Once it has finished installing, you can continue to use your Mac as normal.

    How to clean install macOS Catalina

    We have covered clean installing Catalina in more detail in this article — How to Clean Install macOS Catalina — but here’s a summary.

    1. Make a full bootable clone of your Mac, just in case the worst happens.
    2. Grab a USB stick that’s at least 16GB capacity or an external hard drive.
    3. Erase and reformat the USB stick or external disk.
    4. Create a bootable installer on the disk.
    5. Boot from the new install disk and use Disk Utility in macOS Utilities to erase your startup disk.
    6. Go back to macOS Utilities and choose install macOS, with your startup disk as the location for the installation. 

    Once it’s finished, set up your Mac, reinstall applications and restore your settings.

    My apps are slow or stopped working on macOS Catalina

    Okay, you’ve successfully installed macOS 10.15 Catalina. But some of your apps are no longer available. That’s a heavy blow from macOS Catalina as it no longer supports 32-bit apps. According to Apple, 64-bit apps are more memory-efficient than 32-bit ones. But for most of us, it means we will lose many favorite games and applications, including Photoshop CS. To minimize the damage, you should first check how many 32-bit apps you have. It’s possible to do this with the same Mac maintenance app we’ve mentioned above.

    Next up, click the Updater tab.

    Here you can update your 32-bit apps (and all the rest of the apps) to newer versions. Many developers have already optimized their software for 64-bit architecture. With this method, you’ll update all your software in one go to make it Catalina-friendly. As you can see, I can update 8 apps with just one button. 

    Scan complete and some list of apps shown in Updater tool of CleanMyMac

    Thanks for reading this article. Hope you will like it on Catalina!