If you trying to downgrade your macOS then follow this tutorial to get started successfully. Here we provide a step-by-step guide with images on ‘How to Downgrade macOS.’ In this tutorial, we are taking a case of downgrading from macOS Mojave to macOS High Sierra of laptop/computer. But in case you want to downgrade to other macOS versions, you can follow the same instructions.
Notably, in order to downgrade macOS, you will need to reformat your hard drive. By that, we clearly mean that you can lose all of your data. So please take a backup of all your files before you start the process.
Also, you will need an empty USB flash drive for this process. As we said, you can see the downgrading from macOS Mojave to macOS High Sierra in this tutorial. But as we already mentioned before, you can follow the same instructions if want to downgrade to another macOS version.
How to Downgrade macOS Mojave to Older macOS (Step-by-Step Guide)
1). First, download the macOS you want to downgrade to from the App Store.
2). While downloading, the step may take a while since as you’re downloading an operating system (huge file).
3). If you get a notification like “This copy of the “Install macOS” application is too old to be opened on this version of macOS”, hit Quit. But don’t worry, this is normal since the system will not just let you install an older OS.
4). Now you’ll have to create a bootable USB. Connect your USB flash drive to your laptop/computer and open Launchpad > Other > Disk Utility.
5). Under the ‘External’, select your USB flash drive and press Erase.
6). Now set a name for your drive “boot” (all lowercase without the quotations) and select Mac OS Extended (Journaled) as the Format. Hit Erase.
7). As it is finished, press Done.
8). Now go to Launchpad > Other > Terminal.
9). Copy and paste the following code respective to the macOS version you are downgrading to into terminal and then hit Enter:
macOS High Sierra:
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia –volume /Volumes/boot –applicationpath /Applications/Install\ macOS\ High\ Sierra.app
sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia –volume /Volumes/boot –applicationpath /Applications/Install\ macOS\ Sierra.app
macOS El Capitan:
sudo /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/Resources/createinstallmedia –volume /Volumes/boot –applicationpath /Applications/Install\ OS\ X\ El\ Capitan.app
10). Then enter your password for your laptop/computer and press Enter.
11). Type ‘y’ and hit Enter.
12). Once it is complete, you can exit the Terminal.
13). Restart your laptop/computer and hold down ‘Command + r’ on your keyboard while the computer boots-up.
14). Then you will see the ‘Language Selection’ screen, if do not see this screen, restart your computer and hold down ‘Command + r’ to try again.
15). On the next screen, just go to Disk Utility.
16). After that, Select your ‘Macintosh HD’ under Internal and press Erase.
17). Make sure the format is APFS and hit Erase.
18). Once the process is completed, restart your computer.
Installing New macOS In Your Laptop/Computer (Further Process)
1). After restarting your laptop/computer, hold down the Option key while the computer boots-up.
2). You’ll see an ‘Install macOS’ option, hit Install macOS <OS version>. This step may take a while.
3). Then select your language.
4). Now press Continue and accept the macOS software license agreement.
5). Now select your Mac hard drive and press Install.
6). Now the installation is finished, complete the initial setup and you are done.
Note: This whole process may take more than 3-4 hours, depending on your laptop/computer and internet speed.