I am using the Install macOS Mojave.app installer on my Mac mini (2018) running Mojave 10.14.5 to install Mojave on a formatted external spinning disk laptop drive (a Toshiba model with case).

I successfully formatted the drive using Disk Utility app in the GUID format.

Now when running the Mojave installer, it refuses to install on the external drive saying:

This Mac can only install macOS on APFS-formatted drives.

But I thought APFS was intended only for solid-state drives, not spinning drives. And there was no APFS option in Disk Utility that I could see.

➥ Is it now impossible to install and boot on an external spinning drive?


You are almost there. Check again in Disk Utility app.


You will find APFS as an option in the Format pop-up menu.


You make the same choice of GUID Partition in the other pop-up menu Scheme.

screenshot of Disk Utility > Erase > Format > APFS.

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