How to Downgrade from macOS Catalina to Mojave or Earlier

Did you upgrade to macOS Catalina and decide it’s not for you? Perhaps a favorite app isn’t Catalina compatible, or changes in some of the apps Apple provides are not to your taste. Maybe your Mac just seems to be performing poorly with Catalina, or you experienced issues installing macOS Catalina and would just like to get back to a Mac OS you know works on your Mac.

macOS Catalina installer.

If you would like to downgrade from macOS Catalina to a previous version of the Mac operating system it can be done, but it isn’t always an easy or painless process. If you’re downgrading because of macOS Catalina installation problems, be sure to check the Catalina Install Issues section near the end of this article for any special steps you may need to take.

With those caveats in mind, let’s start the downgrade process.


What You Need in Order to Downgrade from macOS Catalina

There are a few different ways to perform the downgrade; here are two of them. You can:

  • Reinstall a previous version of the Mac OS using the appropriate Mac OS Installer.
  • Use Time Machine to restore from a date when your Mac was using a previous version of the operating system.

With any of the downgrade methods, you’re going to lose all the data currently on your Mac. The volumes that currently house your copy of macOS Catalina will have to be erased in order to convert the two special Catalina volumes (one read-only system volume and one read/write data volume) back to a format that is usable by the earlier versions of the Mac OS.

Back Up Your Current Data

Because of the need to erase your startup drive, the downgrade process should start with backing up all of your data. Time Machine is one option for a backup; just make sure Time Machine has been run shortly before you start the downgrade. The other option is to make a clone of the startup drive. If you go the clone route, make sure the cloning software you use is both APFS and macOS Catalina compatible; Carbon Copy Cloner and SuperDuper are two good possibilities.

OWC Mercury Elite Mini storage system.
Downgrading requires you to completely erase the startup drive. Make sure you have a local backup that you can use to migrate data from.

If you need storage to house these backups, Other World Computing has a large selection of storage options available to choose from.

Don’t forget that besides having a backup of your data you should also have all your passwords, license keys, and network logins saved where you can easily access them during the installation of your replacement Mac OS.

Pick a Mac OS Installer

Unless you’re planning to use the Mac’s Internet Recovery options to reinstall the original version of the Mac OS that shipped with your Mac, or you’re planning on restoring from a Time Machine backup or a clone you made before you upgraded to macOS Catalina, you’re going to need a bootable version of the Mac OS you wish to install.

macOS installers can be downloaded from the Mac App Store.
The Mac OS installers are still available from the Mac App Store, provided you know the download URL.

We can show you how to create the bootable installer, but first you’ll need to download the macOS installer from the Mac App Store. You can find the installers available at:

Download the installer of your choice. If the installer starts up automatically, be sure to quit the installer. Do not allow it to start the install process.

Note: You may see a warning about downloading an older version of the operating system. There should be an option available to continue the download.

T2-Equipped Macs

Creating and using the macOS bootable installer requires your Mac to be able to start up from an external drive. Macs equipped with the T2 security chip need to have a security setting altered to allow the use of bootable external devices.

If your Mac is equipped with a T2 chip, and most current Macs are, you’ll need to check the Rocket Yard guide:

How to Clean Install macOS Catalina

Follow the instructions in the T2-Equipped Macs section.

T-2 equipped Macs have a Startup Security Utility.
You can change the T-2 Security Chip settings from the Recovery utility.

Create the Bootable Installer

You’ll need a USB flash drive with a minimum of 8 GB of storage space and preferably, but not a requirement, a USB 3.0 port.

With the installer downloaded and the USB flash drive in hand, follow the appropriate instructions linked below:

Once you have the bootable installer and a current backup, you’re ready to start the downgrade process.

Erase and Reformat the Startup Drive

Let’s start this section with an important notice:

Warning: This process will completely erase your Mac’s startup drive, destroying all of its content.

Early versions of the Mac OS did not make use of a read-only system volume and a read-write data volume. To ensure earlier versions of the OS can be installed, you need to erase and reformat the startup drive to remove the split volume architecture used in Catalina.

This can be done using the Mac’s Internet Recovery system. You may be tempted to use the normal Recovery volume that Catalina installs on your Mac. The problem is that the Recovery volume is part of the same APFS-formatted drive that houses the system volume and data volume you need to remove. Trying to erase and reformat the drive that also contains the Recovery volume can lead to some interesting error messages that are best to avoid.

Instead, use Internet Recovery, which runs from RAM memory, freeing you to use Disk Utility to completely erase the startup drive. Make sure you have on hand any network or Wi-Fi passwords you may need to make the network connection.

Restart your Mac while holding down the Option + Command + R keys. Continue to hold those keys down until you see a spinning world globe and the words Internet Recovery on the screen. This process takes a while, so be patient.

Use the Recovery's Disk Utility to erase the startup drive.
Be sure to select the startup drive in Disk Utility’s sidebar, and not the Container or Volumes. Remember, this will erase everything on the startup drive.

From the macOS Utilities window that opens, select Disk Utility, then click the Continue button.

In the Disk Utility window, select Show All Devices from the View menu, or use the View button on the toolbar.

In the Disk Utility sidebar, select the Mac’s startup drive (not the volume or the container, but the top-most item in the startup drive hierarchy).

Click or tap the Erase button.

In the sheet that drops down, give the drive a name, set the format to Mac OS Extended (Journaled), and the Scheme to GUID Partition Map.

Note: I’m suggesting Mac OS Extended (Journaled) because it can be used to install Mojave, High Sierra, and Sierra, though Mojave may convert the format to APFS during the installation process.

Click or tap the Erase button.

Once the erase is complete, you can quit Disk Utility.

Tip: If you don’t have a reliable Internet connection, you can use a bootable macOS High Sierra, Mojave, or Catalina installer. Boot from the installer then follow the steps above starting at: “From the macOS Utilities window that opens…”

Install Mac OS

With the startup drive erased, you’re ready to install the earlier version of the macOS.

Connect the bootable macOS installer you made earlier to your Mac.

If your Mac is still booted into recovery mode, quit recovery by selecting Quit macOS Utilities from the macOS Utilities menu. 

Restart your Mac while holding down the option key.

Continue to hold the option key down until you see the Mac’s Boot Manager appear.

The Boot Manager will display a list of connected bootable devices. Use the arrow button to select the USB flash drive that contains the macOS installer. Hit the return key to boot from the installer.

Booting from the USB flash drive may take a while; eventually, the macOS Utilities window will be displayed. Select the option to Install macOS and then click the Continue button. The macOS installer will start up and walk you through the installation of the version of the Mac OS contained on the installer.

Use Time Machine to Downgrade

If you’ve been using Time Machine for your backups, it may be possible to restore from an earlier backup, when you were using an older operating system on your Mac.

The advantage to this method is that not only will you end up with an earlier version of the Mac OS, but you will also have all your data from that time restored as well. (You won’t have any data newer than that date.)

To Use Time Machine to restore from a previous backup point, you still need to erase and format the Catalina startup drive to remove the split system volume and the APFS formatting. Perform the steps outlined in Erase and Restore the Startup Drive, listed above.

Restoring from Time Machine.
You can use Time Machine to restore your Mac to a previous version of the OS, along with all of your user data.

When you get to where you quit Disk Utility, jump back to this point and continue from here.

The macOS Utility window should be open. If not, restart your Mac using the recovery partition, as outlined above.

Make sure your Time Machine backup drive is connected to your Mac.

In the macOS Utility window, select Restore From Time Machine Backup, and then click the Continue button.

The Restore from Time Machine Backup option will present some basic information; once you’ve read it, click the Continue button.

A list of restore sources will be displayed. Select your Time Machine drive and click Continue.

A list of restore points will be displayed, organized by date as well as the OS version that was in use. Select the restore point you wish to use, and then click Continue.

Time Machine will display a list of drives currently connected to your Mac. Select the drive you wish to use as the destination for the restore; this will normally be the startup drive you erased earlier. When you’re ready, click the Restore button.

The restore process will start. This can take a while; when it’s complete, your Mac will restart.

Catalina Install Issues

There have been a number of macOS Catalina install issues that may make it more difficult to downgrade to an earlier version of the Mac OS. We hope one or more of these tips will allow you to perform the downgrade and install an earlier version of the operating system.

Stuck at Setting Up: When your Mac is stuck at the Setting Up point, there’s some good news. The Catalina installation has actually finished, and if you could get past the Setting Up message, you could use your Mac. 

The easiest way around this problem is to just shut down your Mac and restart it. Even if you have to force the power off, either by holding the power button in or unplugging your Mac via the power cord, your Mac should restart and either finish the setup process or, more likely, bring you to the login screen.

Even if you find yourself still stuck at Setting Up, you can force restart the Mac and then enter Recovery mode, as outlined above.

Can’t Download a Version of macOS or Create a Bootable Installer: You may not be able to download or create a bootable installer because your Mac is still not functional due to an install error with Catalina. You don’t have to use your Mac to download or create the bootable installer; it can be done on any Mac, such as the Mac of a friend, family member, or coworker. 

Once you have the bootable installer, you can force restart your Mac and start the downgrade process as outlined above.

Can’t Log In: Make sure you’ve tried restarting, as well as the steps outlined in:

How to Fix macOS Catalina Installation Issues

specifically, the Activation Lock Prevents Access to Your Mac section.

In previous versions of the Mac OS, you could use Single User mode to remove a system file that would force the Mac to run the setup process again, giving you the opportunity to create a new administrator account. Unfortunately, the read-only system volume in Catalina prevents the removal of the file.

If you still can’t gain access, you should consider using the Recovery mode to erase the drive and either reinstall Catalina, or an earlier version of the Mac OS.

Damaged Startup Drive: If the Catalina installation resulted in the startup drive being damaged, you may not be able to make use of the Recovery mode to use Disk Utility to repair the drive.

If you can’t restart into Recovery mode, you can try using Internet Recovery, which doesn’t require a working recovery partition. You’ll find instructions above, in the Erase and Reformat the Startup Drive section.

Once the macOS Utilities window is present, select Disk Utility, and then try the First Aid option.

Video Not Working: There have been a few reports of monitors attached to Macs via an HDMI port not working with Catalina. One workaround is to use a Thunderbolt to HDMI cable so that you can connect the monitor to one of the Mac’s Thunderbolt ports. This should get the display working, and allow you to perform the downgrade or continue to use Catalina.

Now What?

Now that you’ve reinstalled an earlier version of the Mac OS, the hard part begins: deciding which files you want to restore from a backup. You can use the Migration Assistant app to restore files from a clone, another Mac, or a Time Machine backup. Or, you can use Time Machine directly to restore selected files.



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