Installing a new version of the Mac OS is generally a fairly pain-free process; this trend continues with macOS Catalina. Even so, it’s a good idea to review our Rocket Yard guides for a clean install of macOS Catalina as well as an upgrade install of Catalina. You should also take basic steps to ensure you can recover from any install issues you may come across.
The most important of these is to back up your Mac before you start the installation process so that you can recover from any installation issues that may arise.
If you’ve run into an issue and you didn’t first perform a backup, then with any luck, one of our tips will get you back on track. If it does get your Mac going again, remember to back up your Mac before you go any further.
If you need a storage solution to handle your backups, Other World Computing has a large selection of storage options you can choose from.
With backups out of the way, let’s take a look at some of the common and not-so-common macOS Catalina installation issues you may run into:
macOS Catalina Won’t Install
This is the most basic of Catalina installation errors; it simply won’t install. It may be that the installation won’t start, it seems to freeze during the installation, or it never seems to complete.
The two primary causes are; attempting to install on a Mac that Catalina doesn’t support, or trying to install Catalina on a Mac with limited storage space.
Supported Macs: Most Macs from 2012 or later support macOS Catalina. The lone exception is the 2010-2012 Mac Pro, whose graphics cards don’t meet Catalina requirements. You can find a full list of supported Macs in the Rocket Yard guide:
Storage Space: You’ll need about 6.5 GB of space just to download the macOS Catalina installer. After that, the amount of space needed is dependent on the type of installation you’re performing: a clean install or an upgrade install.
A clean install uses up around 20 GB of storage space. In addition, you need to allow for space for your user data, applications, and future updates. As if that weren’t enough, you should keep at least 10 to15 percent of the startup drive free to ensure adequate performance. I normally suggest a good deal more free space than that, but here we’re just talking about a minimum to ensure you can install and use macOS Catalina.
If you’re performing an upgrade install, you need to make sure the startup drive has enough free space for the installer download (6.5 GB), as well as room for the files the installer will copy to the startup drive during installation. It’s difficult to estimate the size of the free space you’ll need since it’s dependent on the version of the Mac OS you’re running before the upgrade. But if you have 25 GB of free space available, you should be able to successfully perform an install of Catalina.
If you’re tight on free space, consider removing unneeded files using one of these methods:
- Tech 101: How to Quickly Free Up Mac Storage Space
- The Files That Make Up the ‘Other’ Storage Category, and How to Remove Them
- Running Low on Mac Storage? Here Are 5 Tips to Recover Some Space
For some of us, even after we clean out unneeded files we’re still short on free space and need to consider upgrading our Mac’s internal drive or adding an external storage system. OWC has you covered if you need to go this route:
Unable to Write Information to Disk
This message (or a variant) will sometimes show up just after you start the installation process, and is most often caused by a corrupt installer file. The simple solution is to delete the macOS Catalina installer and download a new copy.
A new installer will usually take care of the issue, but there’s another problem that could lead to the same message: a damaged target drive for the installation. If you haven’t already done so, you may want to run Disk Utility’s First Aid tool to check and repair the target drive. You should also run First Aid on the startup drive if it isn’t the target for the installation. You can find instructions on using First Aid in:
Could Not Create a Preboot Volume for APFS
The “could not create preboot volume” along with other APFS (Apple File System) errors associated with converting an HFS+ drive to APFS are rarely encountered, an indication of the maturing of the APFS file system.
macOS Catalina requires the use of APFS instead of HFS+. If you’re upgrading from an earlier version of the Mac OS and you were using HFS+, the installer will convert your target drive from HFS+ to APFS. This, in itself, is not an issue. However, in rare occurrences, you may see an error message.
If you encounter this issue, the cure is easy enough: you just need to erase the target drive using Disk Utility. If the target drive was your startup drive, you’ll need to boot into Recovery mode to access Disk Utility. You may also need to restore your Mac’s data using a recent backup before restarting the installation process.
macOS Could Not Be Installed on Your Computer
This may seem like the same issue we started this article with: having a Mac that is supported by Catalina. The difference is that you already verified that your Mac is compatible (see the link to supported Macs above), but you still see the error message.
If that’s the case, open up the Date & Time preference pane and check its settings. Make sure you have both the correct time and the current date properly configured. The best way to ensure that this isn’t a Date & Time issue is to use the option to “Set date and time automatically.” You’ll find this option in the Date & Time tab of the Date & Time preference pane.
Installation Freezes or Failure to Complete
These are actually two issues; the first is the installer freezing during the first phase of the installation process, and the second is when the failure to complete happens after your Mac has rebooted and attempts to load Catalina for the very first time.
In both cases, the first thing to try is to restart your Mac. This fixes the issue for most users experiencing this problem.
Unfortunately, it’s possible that if the installer hangs up at the worst possible spot, your Mac may not be able to restart because of startup drive issues. If this happens to you, you’ll need to use the Mac’s Recovery utility to repair the startup drive using Disk Utility, and/or reinstall the Mac OS or use your backups to recover from.
You can find instructions for using the Recovery utility in the Rocket Yard guide:
Activation Lock Prevents Access to Your Mac
One of the features of newer Macs is the incorporation of T2 Security Chips, which provide a number of useful features, one of which is the ability to erase and deactivate your Mac if it is stolen.
During beta testing, a few people reported that Catalina was failing to complete the installation because it believed the Mac had the activation lock set as if it had been reported stolen. Although I expect this issue to be resolved before macOS Catalina is fully released, if you do come across the issue, here’s how to fix it.
You can correct this issue by using another Mac or iOS device and launching the Find My Mac app, or opening a browser and going to the iCloud.com website. Log in to your iCloud account, if needed, then remove the Mac in question from being associated with your Apple ID.
This should allow you to restart the Mac and complete the Catalina installation.
Unable to Install Catalina on an External Drive
This issue can occur because of the T2 Security Chip found in recent vintage Macs. The T2 chip protects your Mac by default from being booted from an external device. This prevents someone from walking up to your Mac with a USB flash drive, booting your Mac, and accessing your files.
The default settings will also prevent you from installing Catalina on an external drive.
You can find out more about the T2 Security Chip and how to use the Startup Security Utility to configure external boot options in the Rocket Yard guide:
Miscellaneous Fixes for Install Problems
If the install issue you’re having isn’t covered in this guide there are always a few general-purpose tips that may help resolve the problem:
Startup Disk: Occasionally, the startup disk isn’t set or is set incorrectly. In the case of not being set, your Mac may take a very long time to start up as it searches for a device to use to start up from. It may also choose the wrong device to boot from, leaving you wondering what’s going on.
This behavior can explain one problem I’ve seen reported: a Mac that seems to complete a clean install but when the Mac finally reboots, it’s back to the original version of the OS, with no changes. In actuality, the clean install was performed, the Mac is just booting from the wrong startup device.
The fix is to open the Startup Disk preference pane and set the startup disk correctly for your Mac.
Reset NVRAM and SMC: The NVRAM and SMC hold information used by your Mac during startup. If either becomes corrupt, it can cause unusual effects on your Mac. Although resetting the NVRAM and SMC are considered a last-ditch effort to correct a problem, you should still try it because it does work from time to time.
You can find instructions in the guide:
Did You Have Any Catalina Install Issues?
This is our preliminary list of Catalina installation issues you may come across. But as more people perform the upgrade to Catalina, it won’t be surprising to see a few more issues become common.
With that in mind, did you have any issues installing macOS Catalina, and if so, did you discover a fix for the problem?
Leave a comment below and let us all know.
If all else fails with your Catalina install and you want to downgrade, check out our article, How to Downgrade from macOS Catalina to Mojave or Earlier.
If you need to transfer information from a previous version of the Mac OS, take a look at the Rocket Yard guide: How to Use Migration Assistant with macOS Catalina.