Make Final Preparations
Now that you know which basic installation technique you’re going to use, you’re nearly ready to proceed. Your next major step (which could take hours, or even longer) is to obtain the Catalina installer; then I’ll recommend a few other quick, last-minute tasks before you dive in.
Turn Off Anti-Malware Software
In general, anti-malware software doesn’t interfere with purchases and upgrades from the App Store. However, when Apple released Mountain Lion, users reported that the Ad Banner Filter in Intego’s VirusBarrier software sometimes interfered with the process of downloading the installer. Something similar could happen again, and other anti-malware apps could also conceivably prevent Catalina from downloading properly. So, the easiest course of action is to turn off any anti-malware software you may have until you have downloaded Catalina successfully, and then turn it back on.
Obtain the Installer
Depending on your situation, obtaining the Catalina installer may be a trivial matter of a few clicks, or it may be an involved ordeal.
Download on the Destination Mac
If, in your Software Update or App Store Preferences (see Handle Software Updates), the ”Download new updates when available” box is checked, the Catalina installer may already have downloaded without any further intervention. Otherwise, if you have an internet connection that can comfortably download 8.1 GB of data, obtaining Catalina is just like downloading any other app:
Click this link to go directly to the Catalina page in the Mac App Store. (Or, if you prefer, click the App Store icon in your Dock and use the search field to find
macOS Catalina.Click Get, followed by Install. (The wording of this button may vary depending on your version of macOS.)
If prompted, enter your Apple ID and password, and click Sign In.
The Catalina installer downloads to your /Applications folder—a process that could take anywhere from minutes to days, depending on the bandwidth of your internet connection.
After it downloads, the installer launches automatically.
But we’re not ready to install Catalina quite yet, so choose Install macOS Catalina > Quit Install macOS (if you didn’t already do so after an automatic download) to quit the installer for the time being; we’ll return shortly!
If the destination Mac doesn’t have sufficient internet bandwidth, consider taking it to a library, coffee shop, friend’s house, the office, or somewhere else where you can use a higher-speed connection. If you take your Mac to a nearby Apple Store and download Catalina while connected to the store’s Wi-Fi network, the download will be ultra-fast, because it will come from a server within the store.
If your Mac isn’t portable enough to make that feasible, however, there’s another option…
Download on Another Mac
You need to get the Catalina installer onto your Mac somehow, but you need not download it from the App Store directly onto the Mac where you’ll install it. You can download the Catalina installer on another Mac, and then copy the installer to your Mac over a network or by way of a USB thumb drive, a portable hard drive, or some other media.
Although there are many ways to do this, the basic steps you’d want to follow are these:
On the other Mac—the one where you’ll download the installer—open the App Store app.
Download Catalina, as described in the previous topic.
Copy the installer from
/Applicationsonto the external media of your choice.
Copy the Installer to a Safe Place
Unlike most software that you download from the App Store, what shows up in the /Applications folder after you download Catalina is an installer (an app called Install macOS Catalina); you must run the installer to put all the necessary pieces in place. During this process, something surprising happens: the installer is deleted! That’s right—once Catalina is up and running, if you look in /Applications, the installer will be gone.
I presume the reason for this is that once Catalina is installed, Apple wants to give you back the 8.1 GB or so of disk space the installer was taking up, since you likely won’t need the installer in the future (and can download it again if you do). But what if you want to install Catalina on multiple Macs—or reinstall it later on the same Mac—without having to download that huge installer again? I’ll tell you what: you’d better put that installer in a safe place before you run it!
Now, before going any further, I should add some nuance to the “Catalina installer deletes itself” concept. The installer deletes itself only when both of the following are true:
The installer is in
/Applicationson your startup volume.You do an in-place upgrade of your startup volume.
If you put the installer anywhere else—your desktop, ~/Downloads, or wherever—it won’t be deleted after it runs. Even so, because that big file is valuable, I urge you to make a copy just in case the unexpected should happen.
So, before you do anything else, you should either ⌘-drag the installer to move it from /Applications to another location (so it won’t be deleted automatically, no matter what), or Option-drag the installer to copy it to another location—preferably another volume—so if it is deleted, you’ll have a spare. Or, create a bootable installation volume, as I describe next.
Make a Bootable Catalina Installer Volume
This step is entirely optional, but some people find it useful.
The Catalina installer doesn’t include or require boot media. But you might want to have a copy of the installer on a bootable disk as a backup, to simplify installing Catalina on multiple Macs, to install Catalina on a Mac without Lion or later, or for other reasons.
The easy way to create this sort of disk is to use an app that does all the work with a few clicks—all you’ll need is a blank USB thumb drive, SD card, external hard drive, or other storage device with a capacity of at least 8 GB. Two apps that can do this, both free, are Install Disk Creator and DiskMaker X. However, as of publication time, neither had been updated yet to work with Catalina.
The other option is a command-line tool called createinstallmedia that is buried inside the Catalina installer (and thus is a method that Apple officially sanctions). Using this tool requires mucking around in Terminal, but it requires no help from third-party apps. You can find many tutorials on the web about how to use the command-line approach—for example, this one by Jeff Benjamin at 9to5Mac.
But there’s a catch, in that a bootable installer requires a full Catalina installer to work with, and in some cases, that may not be what you get when you download Catalina, as I explain in the sidebar ahead.
Update Your Duplicate (Again)
Earlier in this book, I instructed you to make a bootable duplicate of your startup disk and then—after performing some cleanup tasks—to update that duplicate so it reflects the current state of your disk. If you did that just minutes ago—and your bootable duplicate includes the Catalina installer file located outside of the /Applications folder—then you can move along to the next step. Otherwise, I suggest updating your duplicate one last time before running the installer.
Turn Off (Yes, Off) Automatic Duplicates
Picture this: shortly after you upgrade to Catalina, your backup software (which is still installed, natch) runs at its scheduled time, overwriting your bootable duplicate with a copy of your Catalina installation. And then, an hour or two later, you discover that Catalina has a major problem that requires you to go back to your previous version of macOS. But oops! The backup of your older system is already gone.
So, although you should certainly continue updating your duplicate after Catalina is installed, either do so using a new backup drive or wait a few days or so to make sure everything is working well enough under Catalina that you are unlikely to go back to your old system. Then, and only then, turn automatic duplicates back on.
Make a Copy of This Book
You’ll want to refer to this book while you perform your installation, especially if something goes wrong during the process. If you are reading on the Mac where you’ll be installing Catalina, you should either copy it to another computer, iPhone, iPad, or other mobile ebook-reading device, or print portions of it.
For tips on copying this book to a mobile device, read Device Advice (popular methods include Dropbox and downloading directly to the mobile device from your Take Control account). To download this book in a different format, click the link in Ebook Extras.
If you print to paper, you can limit the printout to just these chapters (as appropriate to your situation): “Upgrade Using Plan A: In-place Upgrade,” “Upgrade Using Plan B: Clean Install,” “Perform Post-installation Tasks,” and “Troubleshoot Upgrade Problems.”