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How to Prepare Your Mac to Upgrade to macOS Big Sur

Posted on August 25th, 2020 by

Another year, another new version of macOS. In a couple of months, you’ll be able to upgrade your Mac to macOS Big Sur, also known as macOS 11. The forthcoming version of Apple’s desktop operating system features the biggest interface change since the release of Mac OS X, and, while there aren’t a lot of flashy new features, everything will look different.

Should you upgrade your Mac to Big Sur? Is your Mac compatible with the new operating system? And how should you prepare for this big change? In this article, I’ll answer all those questions, so you can be ready to upgrade your Mac to macOS Big Sur when Apple officially releases its new operating system.


The first thing to check is whether your Mac is compatible with Big Sur. Any Mac released in mid 2012 or later will be able to run Big Sur, and some older Mac Pros will also be able to run it.

  • MacBook Pro (Late 2013 and later)
  • MacBook Air (2013 and later)
  • MacBook (2015 and later)
  • iMac (2014 and later)
  • iMac Pro (2017 and later)
  • Mac Mini (2014 and later)
  • Mac Pro (2013 and later)

If you’re not sure of the vintage of your Mac, go to the Apple menu, and choose About This Mac. You’ll see its model and year.

Check Software Compatibility

All of Apple’s software will be compatible with Big Sur on launch day, and many major apps will as well. But there’s a possibility that one or more apps that you depend on won’t be. App developers always have several months to ensure the compatibility of their products, but, in some cases they don’t work quickly enough, or it’s not possible to make their apps compatible.

It is essential that you check to make sure that your apps are compatible. Imagine if you don’t, and you find that one app you use to perform in important task for your clients doesn’t work? You’ll have to use your backup (see below) to revert to Catalina.

Apple does not maintain a list of compatible apps, but you can find lists in various places, such as this Reddit thread. Each app developer should say on their websites, or in Mac App Store information, whether they are compatible. But in some cases, you won’t know until Big Sur launches.

It’s especially important that you check that any hardware drivers you rely on are compatible. For example, if you use a RAID storage device, and its driver isn’t updated, you won’t be able to access your files on that device; and if you have a graphics card whose drivers are not part of macOS, you’ll need to make sure they have been updated to use your Mac correctly.

Clean Your Mac

It’s a good idea to update as much of your software as possible before upgrading to Big Sur, because in many cases updates will be available that are compatible with the new operating system before its release. Most apps these days offer automatic update features, or, if you’ve purchased them from the Mac App Store, you can get updates via the App Store app. This is especially important for apps like Microsoft Office, or Adobe’s Creative Cloud apps, and other apps you depend on for your work.

Another thing you can do is clean out some of the gunk that has been on your Mac for a while. You can start by choosing the Apple menu > About this Mac, then clicking on Storage. (RELATED: How to Use Optimized Storage to Increase Disk Space.)

You can also use Intego Washing Machine to clean up and delete files you no longer need, such as cache files, downloads, duplicates, and more.

Check Your Drive

Apple’s Disk Utility (located in /Applications/Utilities) is a tool designed to manage disks, but also to check them for errors. Before upgrading, it’s a good idea to run Disk Utility’s First Aid tool on your startup volume, as well as on the disk(s) you will use to back up your Mac (see below).

Launch Disk Utility, select your startup volume, then click First Aid in the toolbar. This will take a few minutes, and during the process your disk will be locked so Disk Utility can make repairs, if necessary. When this is completed, it will tell you if all is well, and if it has made repairs.

Back Up Your Mac

If your Mac is compatible, and you’re ready to upgrade, the first thing you should do is back up your Mac. You can use Time Machine if you have an external hard drive, but the safest way to do this is to clone your drive. A clone, or bootable backup, is an exact copy of everything on your Mac’s drive: system files and personal data. You can do this with Intego Personal Backup. (Related: Intego Personal Backup Compared with Apple’s Time Machine)

If anything goes wrong during the upgrade process, you can boot from the external drive, and, if necessary, recopy all its files to your Mac.

Choose Upgrade Method: Migration or Clean Installation

There are two ways to upgrade a Mac. The simplest is to run the macOS Big Sur installer, which will install the new files over your existing operating system. It won’t alter your personal data, but only those files that are part of the system, as well as bundled Apple apps.

The other is to use Apple’s Migration Assistant. This app is designed to move your data from an old Mac to a new one, but you can also use it for an upgrade. To do this, you should clone your Mac, on at least two drives (one to use for the upgrade, and another as a backup). Start up your Mac, then press the Option key immediately so you can select a cloned drive as the startup drive. Launch Disk Utility (in /Applications/Utilities) and erase the drive on your Mac. (You did make two backups, right?)

Download the macOS Big Sur installer and launch it. It will ask which drive you want to install the software on; select the now erased drive in your Mac. Follow the instructions to complete the installation.

When you’ve finished, you’ll have a virgin operating system on your Mac, and you’ll still be working from your external drive. You can now copy all the files in your home folder, as well as personal apps. (RELATED: Setting Up a New Mac: Should You Migrate or Do a Clean Installation?) 

A clean installation is time consuming, but it can weed out old files from apps you no longer use, and it’s a good way to start with a clean slate. Some people do this for every major operating system upgrade; I only do it every few years, because it does take a long time. If you do a clean installation, make sure to keep both of your clones for some time, just in case there’s something you forgot to cop over.

How to Install macOS Big Sur

Okay, it’s taken a while, but now you’re ready. If you’re installing macOS Big Sur on a laptop, make sure it’s charged, or connect it to a power supply; you don’t want it running out of battery during the installation process.

Go to the Mac App Store and download the Big Sur installer. This is about 5-6 GB, and may take some time depending on your bandwidth. When the download is complete, the installer will launch; follow its instructions. The upgrade process can take a while – a half hour or more – and this is a good time to get a cup of tea or coffee, walk the dog, or do something else instead of sitting in front of your Mac watching its progress bar.

But first… In general, after macOS is installed, the installer is deleted. If you look in your Applications folder, you’ll see the installer, called Install macOS Big Sur. It’s a good idea to copy it to another location, an external drive, or, perhaps, your Downloads folder. This way you’ll have another copy in case something goes wrong and you need to run it again. If your bandwidth is fast enough, this may not be necessary, but for many people it can save a lot of time to keep the installer safe. This is also useful if you have more than one Mac; you can just copy the installer to another Mac and run it.

Once the installation is complete, you’ll need to go through a few screens, such as one to sign into your iCloud account. At this point, you may see an Incompatible Software screen telling you of apps that have been moved because they are known to be incompatible. You’ll find them in an Incompatible Software folder at the top level of your drive.

What to Do if Something Goes Wrong

Many things can go wrong with an operating system upgrade. If you have a problem, you can boot your Mac from the clone you made earlier, then run the installer again. In a worst-case scenario, you may need to wipe your Mac’s startup drive, the follow the clean installation method I discussed above.

Even if all is well, keep those clones for a while, just in case something goes wrong in the first few days of using Big Sur. But now, you can start checking out the new features in this new operating system and plan for your upgrade. Enjoy!

About Kirk McElhearn

Kirk McElhearn writes about Macs, iPods, iTunes, books, music and more on his blog Kirkville. He is co-host of the Intego Mac Podcast and PhotoActive, and a regular contributor to The Mac Security Blog, TidBITS, and several other websites and publications. Kirk has written more than twenty books, including Take Control books about iTunes, LaunchBar, and Scrivener. Follow him on Twitter at @mcelhearn. View all posts by Kirk McElhearn →