Unable to Install Catalina- An Error Occurred Installing macOS Catalina

Fix Errors Installing macOS Catalina

There are multiple Mac users who are having trouble installing macOS Catalina. A few errors which mac users are receiving are “An error occurred installing the update” or “The update has been deleted since being downloaded from the Apple Software Update server. An error occurred while installing selected updates” or “This volume is not formatted as APFS” or “unable to verify”. Be it any error, if you are unable to install Catalina on your Mac then you are in the right place. Follow the steps provided in this post and any one of the steps should help you to install Catalina on your Mac Successfully. Let us start with practical scenarios.

Scenario 1: “An error occurred installing the update” (10.15.3)

That is the radio box message that I get every time that I’ve tried to install this update. Any thoughts or suggestions?

Source: Apple Community

Scenario 2: Unable to install Catalina- Unable to Install Catalina- An Error Occurred Installing macOS Catalina

I’m using a mid-2012 MacBook Pro 15″.  Catalina won’t install because I don’t have the APFS file system, but the option to change over to it is grayed out.  I tried booting to the online recovery program, and it doesn’t have the option to install APFS either.  I even downloaded a new version of Mojave and attempted to install it from an external drive, and the APFS option was grayed out there too.  Apple support told me that my firmware is optimized for an HDD, so since I have an SSD it won’t install.  I’m considering hooking up an HDD and loading my last Time Machine backup, then seeing if I can upgrade to Catalina, do another Time Machine backup, then load that onto the SSD.
Scenario 3:  This volume is not formatted as APFS
I am unable to install Catalina. I’m currently running Mojave 10.14.1. When I try to install Catalina it says “This volume is not formatted as APFS” What should I do? Thanks!
Fix This volume is not formatted as APFS

Check the System Compatibility

Users with OS X Mavericks or later can install macOS Catalina without any issue. In order to install Catalina, your Mac needs 4GB of memory and 12.5GB of available space. To check system compatibility in detail visit this link.

After you are aware that your Mac is compatible, launch the macOS Catalina page on the App Store. Click the Get button to download.

After download, the installer will launch, select Continue and follow the onscreen instructions to install macOS Catalina.

Turn Off/Remove Anti-virus Program

Antivirus program installed on your Mac sometimes may conflict or stop Catalina files to install it on your Mac. You may disable or uninstall the antivirus program on your Mac while downloading or installing a macOS Catalina.

Install Catalina in Internet Recovery Mode

Many users were able to install macOS Catalina in Internet Recovery mode, backup all your data just to be on the safer side.
  • Download Catalina.
  • Boot into Internet Recovery Mode using Command + Option + R.
  • On macOS Utilities, select Disk Utility.
  • Select your Drive volume and Unmount.
  • Convert to APFS.
  • Quit Disk Utility.
  • On macOS Utilities, select Reinstall macOS and install macOS Catalina.
Following the above steps helped users to get rid of the error: This volume is not formatted as APFS.

Install Catalina Under New Administrator Account

Sometimes current profile may go corrupt and creating a new admin account may help you to install Catalina successfully.

Follow the steps provided below to create a new admin account.

Go to the Apple menu and select System Preferences.

System preference mac

Click on User & Groups.

System preference mac

Now select the lock icon, enter the user name and password of an existing admin account and open preference panel.

Lock icon mac

Click on the + plus icon to create a new account.

Plus icon mac

Bring down the drop-down menu next to New Account and select Administrator

Admin mac

Enter all the necessary details required for the new Administrator account such as complete name, user name, password, and a password hint, click on Create User to create a new Administrator account.

Create new admin mac

Once created, restart your Mac and log in to the new administrator account and download the Catalina installer from the Apple app store. Now macOS Catalina should install successfully. In case you face any error, try disabling the firewall. Go to the System Preferences > Security & Privacy > Lock button in the bottom left > Turn Off Firewall.

After the installation finishes, log out and switch to your previous admin account. You can remove or delete the new admin account and it’s home folder if you want to.

Install macOS Catalina to Macintosh HD Main Drive

If your Mac has multiple hard drives installed, then make sure that you are selecting the main Macintosh HD drive to install the macOS Catalina.

Macintosh HD Drive

Use Ethernet Connection

Please ensure that your internet connection is stable during the download of macOS Catalina. Wired connection is more stable when compared to Wi-Fi connection.  You need an adaptor to connect an ethernet cable on your Mac. Try downloading and installing Catalina after switching to a wired connection.

Ethernet connection

Use Safe Mode to Install macOS Catalina

Safe mode provides a restricted environment and allows only necessary files to load up. Due to this third party programs which may be the cause of installation failure will no longer interfere with the Catalina installation.

Go to the Apple menu and click on Restart.

Apple menu restart

Press and hold the Shift key on the keyboard while Mac is restarting.

Once Mac is in safe mode. Open Mac App Store, download and install Catalina.

Mac App Store

Install macOS Catalina Using USB Flash Drive

If nothing works then going for a clean installation of macOS Catalina would be the best way to avoid any kind of installation issue. Just make sure that you backup all your data before going for clean installation as this will erase all the data on your Mac. To learn how to install macOS Catalina using USB flash drive visit this Apple link How to create a bootable installer for macOS.

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Bonus Tip: Number One Mac Data Recovery Program

In case you lose your precious data during the installation of macOS Catalina then you can use Mac Data Recovery which can help you to recover your lost files when you do not have a backup.

Download and install the Mac Data Recovery tool. Launch Mac Data Recovery tool, choose the particular drive where you lost the data.


Select drive on mac

Scan the drive to find your lost files on your Mac.

Scan drive on Mac

Preview the lost files after the scan is complete. Click on Recover and recover the lost files on your Mac.

Recover lost files on mac
Wrap Up
I hope this post helped you to install macOS Catalina on your Mac Successfully. In case still, you are unable to install Catalina then please contact Apple support for further assistance.
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