How to Downgrade from Catalina to Mojave Using Time Machine
Time Machine is macOS’s built-in backup utility. And if you want to return to Mojave after you’ve upgraded, it can help you with that, too. If you realize soon after upgrading that you want to downgrade macOS, you can restore a backup from before the change. This technique has a time limit, unfortunately; you have to use it before the program dumps the old backup.
Connect your backup hard drive to your Mac. Restart (or start up) your Mac while holding Command+R. You can release the keys when the Apple logo appears. The macOS Utilities window will open. Select Restore from Time Machine Backup and click Continue. When the Select Restore Source window appears, highlight your backup drive and click Continue. Enter your user password to access your disk (if it’s encrypted). On the next screen, select the backup you want to use. Look for one that has 10. 14 in the macOS Version column. That’s the release number of Mojave. Click Continue to proceed. On the next screen, select the destination (typically your Mac’s built-in hard drive) and click Restore. Your Mac will restore that backup and then restart with macOS Mojave installed.
How to Downgrade from Catalina to Mojave with an Installer
If you don’t have a Time Machine backup with Mojave, you still have some options. The following process uses an attached disk or even a flash drive (assuming it’s a big enough flash drive) to be the drive you install Mojave from to your current system.
Back up your computer. You’re going to delete your hard drive during the downgrade, but if you do a backup immediately beforehand, you won’t lose any files when you restore later. Select About this Mac under the Apple Menu. Click System Report. Select Controller. If the Model Name field says Apple T2 Security Chip, you’ll have a few more steps to follow. If not, go to Step 11. Restart your Mac and hold Command+R until you see the Apple logo. When the macOS Utilities window appears, select Startup Security Utility under the Utilities menu in the toolbar. Enter your administrator password if you receive a prompt. Make sure that the box next to Allow booting from external media has a check in it. Restart your computer again to return to normal mode. Download macOS Mojave from the Mac App Store by going the Mac App Store and click Get. Click Download to confirm. You’ll get an alert saying that the installer is too old to run in your version of macOS, but your computer will still add the installer to your Applications folder. Connect the drive you want to create your installer on to your Mac. You need at least 16GB on the drive to create the installer. You can also partition an external hard drive. Open Disk Utility from Utilities in your Applications folder. Select the drive you want to create the installer on. Select Erase if you’re using a new drive, or Partition if you’re using part of an existing one. If you chose to Erase a new drive, enter a new name for it (e. g. , “Mojave”), set the format to Mac OS Extended (Journaled), and click Erase. Skip to Step 20. Alternatively, you can format the drive as APFS. If you chose to Partition, click the plus sign on the screen that opens. Name your partition, set a size for it (at least 16 GB), and format it as Mac OS Extended (Journaled). Click Apply to create the partition. Open Terminal from Utilities in your Applications folder. Type the following command into the Terminal window, replacing “[DriveName]” with the name of the disk or partition you just created. sudo /Applications/Install\ macOS\ Mojave. app/Contents/Resources/createinstallmedia –volume /Volumes/[DriveName]–applicationpath /Applications/Install\ macOS\ Mojave. app Enter your administrator password and press Return. Press Y to erase your drive (again) and create the installer. Disconnect your drive and restart your computer while holding Command+R until you see the Apple logo. When the macOS Utilities window appears, select Disk Utility and click Continue. Select your hard drive under Internal and click Erase. Enter a name for your hard drive, format it as Mac OS Extended (Journaled), choose GUID Partition Map under Scheme, and then click Erase. Once your hard drive is empty, reconnect the drive with the Mojave installer and restart again while holding Option. Select the drive containing Mojave and click Continue. Your Mac will install Mojave and start up. To restore your files, open Migration Assistant under Utilities in your Applications folder. Migration Assistant will close all other programs while it’s running. Authorize Migration Assistant to make changes to your Mac. Select From a Mac, Time Machine backup, or startup disk and then click Continue. Select the drive you use for Time Machine and click Continue. Select the particular backup you want to restore and click Continue. Select the information you want to transfer, and then click Continue to finish the process. You’ll probably want to transfer all of the available information.
How to Downgrade from Catalina to Mojave by Restoring Your Computer
The above instructions work for most cases in which you’d go back to Mojave. But you may have another option available to you: If your computer shipped with Mojave pre-installed, you can restore it by skipping a lot of the above steps.
If not, go to Step 11.
Skip to Step 20.
Here’s how to downgrade from Catalina to Mojave by restoring your computer.
Back up your computer using Time Machine. Restart your computer while holding Command+R to enter Recovery Mode. Select Disk Utility and click Continue. Select your internal hard drive and click Erase. Enter a name for your hard drive, format it as Mac OS Extended (Journaled), choose GUID Partition Map under Scheme, and then click Erase. When your hard drive is empty, restart again while holding Shift+Option+Command+R. Your Mac will start up and install the version of macOS that came with your computer. Restore your files using Migration Assistant, following Steps 31-36 above.
