July 11, 2018

Installing MacOS on Older Macs

I happen to have an older MacBook Air from 2011. Recently I installed Ubuntu on the device to test how well or not this works. (It does work well enough!) However, I decided to go back to MacOS.

As I wiped the entire hard drive of my Mac I used the network installer to get back a working system. However, I found that this installer installed a version of MacOS from the times when they still named their OS versions after large felines.

Luckily you can use a second Mac to create a bootable thumb drive of the latest MacOS version and just do a fresh install… Versions older than High Sierra were shipped to customers in a large (5.5 GB) .app file. Now Apple are using a small network installer app. This is bad news as you need the large “all-in-one” installer to create the bootable drive.

Luckily there is a tool that you can use to download the “fat” installer from Apple: http://dosdude1.com/highsierra/. Just download the tool, select “download” from the tools menu and wait.

Once done, insert your thumb drive and do something like sudo /path/to/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Mountpoint --applicationpath /path/to/Install\ macOS\ High\ Sierra.app. Note that you must adapt the paths according to the place where you put the fat installer and where your thumb drive is mounted (nothing like /dev/sdx).

After a good while you should end up with a working installer on the thumb drive that you can use to install the machine.

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