How to install older macOS versions using the Terminal app

With macOS Catalina out now, most users will have already updated to the new version of the operating system. However, some users might have felt the need to downgrade to an older version. There could be many reasons for this, such as the system running slow, apps not working properly, or a specific program you want that does not support the new version. Although the older versions will be listed in the Mac App Store, it is possible that those options won’t work. In such cases, you should know how to install older macOS versions using the Terminal app.

install older macOS

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Why use Terminal app?

Terminal is a useful app to install older versions of macOS or OS X. You can even get the new versions of macOS from this app. Although installing an older version of the OS or a new update is a simple process using the App Store, often older versions of macOS will be listed as “unavailable” when you try to download them from the App Store.

For such occasions, you can head to the Terminal app to download the macOS version of your choice. The app is also useful for developers who need to run their apps on older versions to check their stability.

Before we detail how to install an older macOS version using the Terminal app, first you should determine if your Mac supports the macOS or Mac OS X version you want to install. In theory, your Mac should run all versions of macOS or mac OS X that came before you purchased the Mac and the versions released a few years immediately following the purchase.

If you are planning to install an older version of macOS on an older Mac, then you shouldn’t face any difficulty. However, it has been seen that installing a newer version of macOS on an older Mac could be problematic. Usually, newer versions of macOS drop support for the older Macs.

Similarly, you may face issues when installing an older version of macOS or OS X on a newer Mac. This is because the drivers for the new hardware may not be available for the older macOS version. Thus, it is advisable that you check beforehand if your system supports the macOS version you plan to install.

How to prepare your Mac

Once you determine that your Mac supports the version you want to install, the next thing to do is prepare your system for the installation. You can do this by checking the version you are running currently and ensuring that your device has enough space to download the older version.

To check the current version of the operating system, click on the Apple menu icon in the top-left corner of the screen, and then select “About This Mac.” Clicking on the “Storage” tab will bring up information on available disk space. If there isn’t much space, then free up some space before downloading the version of the OS you want.

Now that you have created space, the last thing is to take a backup of all your important data. You can take the backup either on cloud storage or an external drive. You can also use a specialized tool to take a backup.

How to install older versions of macOS using Terminal app

Once you are through with the above things, you are now ready to learn how to use the Terminal app to install older macOS versions. Follow these steps:

  1. Go the Terminal app from the Applications > Utilities folder.
  2. Depending on the macOS version you want to install, type either of these commands. If you want to download the latest macOS version, then type this command: “softwareupdate —fetch-full-installer.” If you want to download an older macOS version, then type this command: “softwareupdate —fetch-full-installer [build number].” For example, if you want to download version 9.0, then type the following command: “softwareupdate —fetch-full-installer 9.0.0.”
  3. Now execute the command by tapping the Return key.
  4. The file will automatically be downloaded to the Mac’s Applications folder. Once the download is finished, open the file to start the installation process and then follow the on-screen instructions to complete the process.

Alternatively, you can also download older macOS versions from Apple Support’s Downloads page. On the download page, you can easily search for the version you are looking for. Most of the OS versions are available to download for free.

If the macOS version you are looking for isn’t available on Apple’s site, another way is to get it from a friend who is running the macOS version you are looking for. All your friend has to do is make a copy of the installer file. You can also head to a torrent site and download a .dmg file, but this method is not the safest. One other way is to head to the nearest Apple Store and get the image file of the macOS version you are looking for.



About the Author

Aman Jain
Aman is MBA (Finance) with an experience on both Marketing and Finance side. He has worked as a Risk Analyst for AIR Worldwide, and is currently leading VeRa FinServ, a Financial Research firm. Favorite pastimes include watching science fiction movies, reviewing tech gadgets, playing PC games and cricket. - Email him at amanjain@valuewalk.com