Find an OS Version You Need in the Purchased Section
- Go to the Purchased section in the App Store (go to Store -> Purchased). Here, you’ll find previously bought versions of Mac OS X and macOS. However, if you never downloaded the version you need right now, it won’t show up in this list.
- Hit Install.
If You Can’t Find the Needed OS Version, Read This SectionIf you haven’t found a Mac OS you need in the purchased section, log out of the Apple Store and then log in again. If, after you’ve logged in back, you don’t see the needed version, there is a great chance you’ve downloaded it using another ID. If you don’t remember the ID you used then, just find someone who has installed it and can share it with you. After you have found the needed version, there are some scenarios, and you need to select one.
Install a Mac OS via Bootable Installer
- On an external storage device, create a bootable installer using the installation file. Make sure the drive has at least 8 GB of free space.
- Erase all the info from your Mac and bring it back to the factory settings.
- Install the older OS version using the installer file you have created on the external drive.
- Recover your Mac with a Time Machine backup which precedes the installation of new macOS.
Install Older Mac OS on an External StorageThis way lets you run older Mac OS version via an external drive. You need to install a bootable version of older Mac OS on an external hard drive. After it’s done, hold down Option + Alt when you start up Mac and choose to boot from an external storage device.
Run older Mac OS via Virtual Machine like VMwareBefore we start, you need to choose a virtual machine from a huge number of software packages. For instance, you can try VMware, Parallels, Boot Camp, or Virtual Box. Once you’ve selected one, do the following:
- Download the installer of an older Mac OS version.
- Create a new VM on Mac.
- Install an older version of Mac OS on this VM.