I made a mistake.

I always keep telling everyone to have automatic updates turned on if you have a Mac, and in most cases, this is good advice.

However, I knew that the macOS I had before upgrade – Mojave – is the latest OS that still supports 32-bit apps. Apple warned me when I ran those apps that I have to make sure to upgrade to 64-bit versions if possible because the next OS will drop the support for my old applications.

As soon as I knew this, I supposed to turn off automatic operating system updates, but I didn’t.

As a result, my Mac updated to macOS Catalina, and I lost the ability to run my older apps. And I can’t upgrade because they are not supported anymore, and there had no 64-bit versions for me to switch.

If you are in the same situation as me, if you have some programs that you must have and Catalina doesn’t allow them to run, you are thinking about downgrading from Catalina back to Mojave.

You basically have three options to solve the issue.


Option 1 to Downgrade macOS Catalina to macOS Mojave

While I forgot to turn off auto OS updates in System Preferences, I was still lucky because I keep taking Time Machine backups periodically. If you have backups taken before the upgrade, restoring from a backup is by far the best option you have. 

The great thing about Time Machine backups is that you can restore the entire disk image, including all apps, documents, and even the operating system.

In order to restore a backup here’s what you have to do:

  1. Restart Mac in a Recovery Mode. First, shut down your Mac. Then press Option (Alt) and R keys simultaneously. Start your Mac without releasing the keys. Keep pressing Option+R keys until the Apple logo appears on the screen. Now you can release the keys.
  2. In the menu on the screen, find and click on “Restore From Time Machine Backup.”
  3. Select the disk where the last backup is stored.
  4. Select the date and time you want to restore. 

The Time Machine will erase the primary disk on your Mac and copy a disk image prior to the Catalina upgrade.


Option 2 to Downgrade macOS Catalina to macOS Mojave

I understand that most people will not be as lucky as me and wouldn’t have a backup ready.

In this case, the process is much more complicated and involved.

Saving Data Before Downgrade

The problem with macOS upgrades is that Mac does not allow to install earlier OS versions. So your only option is to erase the disk and install Mojave as a new install. With this approach, as you probably understand, you lose all your documents and all your apps.  What should you do then? 

You have multiple ways to save the data:

  1. Install DropBox or another cloud sync program. Copy all your documents to the DropBox folder and make sure that they have all been uploaded to the cloud. This approach works for someone who only cares about the documents and can restore apps from external media.
  2. Use a backup solution such as Get Backup Pro and save the folders you need or better the entire disk.


 Create Bootable Mojave Disk

For this, you will need either an external disk or a thumb drive. Before using the device, you have to make sure that it was formatted with a compatible Mac format. It also must have at least 10GB free space.

1/ The next step is to download Mojave. Use the following link: https://apps.apple.com/

If you open the link in Safari, it will ask to open the app in the App Store. Click Ok. The download process will begin. Once downloaded the Mojave installer will attempt to run but will fail with the error “This copy of the ‘Install macOS’ application is too old to be opened on this version of macOS.” Which is expected as I warned before.

2/ Now plug in the external device and start the Terminal app. Copy the following command to the Terminal app:

sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia –volume /Volumes/[Volume_Name] –nointeraction

Make sure to replace [Volume_Name] with the name of the external disk or thumb drive. In my case, then the name of the USB flash drive was “ESD-USB”, so the command was following:

sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia –volume /Volumes/ESD-USB –nointeraction

3/ Run the command. You would need to enter the Admin password when asked. This command will copy the installer media to the external drive.

Installing Mojave

Once you have a bootable installer drive ready, you need to restart in Recovery mode again.  Follow the same steps as above.
Once in the Recovery Mode, start the Disk Utility app.
Click on the startup disk (most likely it is called Macintosh HD). Click Erase.
After the erasing process is done, click on Restart.
Immediately press the Option key.

When Mac starts, it will ask which drive to use to boot. Choose the bootable Mojave drive you have built above.  Click Continue and wait until Mojave finishes installing.


Restoring documents and apps

Depending on which backup mechanism you chose previously, the restore process will also vary. If you saved documents in DropBox, you need to install the DropBox program again, sign in to your account and wait until all documents get synced down to the disk.If you used either Time Machine or Get Backup Pro, use the program directions to restore folders or documents.


Option 3 to Downgrade macOS Catalina to macOS Mojave

As you can see, the process of downgrading a macOS is very complicated. You need to be technical savvy, in order to perform all steps. You need to know such things as backups, Terminal app and Mac recovery mode. The worst thing is that there is a high chance of losing data and apps if anything is not done properly or out of order. 

If you are not sure that you can do the OS downgrade yourself, I would recommend a specialist to do it for you. 

For instance, if you live in San Diego, CA area the obvious choice to contact SD Bytes Computer Repair for help. They offer Data Recovery service, which you can use even if think that the data is permanently lost.


We reviewed three approaches to take when your Mac was upgraded to Catalina accidentally. Choose the one that you think is best to preserve the data on your Mac.

And don’t forget about the final change. Make sure that “Install macOS updates” checkbox is unchecked in System Preferences -> Software Update -> Advanced section.


Or otherwise, you will have to go through the same process again a week later.


About the author:
Al Abdukadirov – is a founder of MacMyths.com.  You can reach him at
email: al@macmyths.com
web: https://macmyths.com