I wanted to install macOS High Sierra on a virtual machine on my Mac so that I could debug some issues. The host machine is running macOS and the guest VM would be running macOS as well.

VirtualBox does not support APFS right now and neither does Parallels Lite. This is a problem since APFS is the default for macOS High Sierra.

Although it should be possible to install macOS High Sierra in VirtualBox on an HFS+ disk, I could not get it to work with VirtualBox. However, I was able to get it working with Parallels Desktop Lite (after a couple workarounds).

I am assuming you are comfortable working with the command line, and already have a High Sierra installer available to you and downloaded on your Mac.

First, generate an .iso file from the High Sierra installer (thanks to some helpful guides for showing me how to do this).

Run each of these commands one after another. If something goes wrong, you can reboot to clear things out and try again. 

hdiutil create \
	-o /tmp/HighSierra.cdr \
	-size 7316m \
	-layout SPUD \
	-fs HFS+J

hdiutil attach \
	/tmp/HighSierra.cdr.dmg \
	-noverify \
	-mountpoint /Volumes/install_build

sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia \
	--volume /Volumes/install_build \
	--applicationpath /Applications/Install\ macOS\ High\ Sierra.app \
	--nointeraction

hdiutil detach \
	"/Volumes/Install macOS High Sierra"

hdiutil convert \
	/tmp/HighSierra.cdr.dmg \
	-format UDTO \
	-o /tmp/HighSierra.iso

mv /tmp/HighSierra.iso.cdr ~/Desktop/HighSierra.iso

rm /tmp/HighSierra.cdr.dmg

Install the Parallels Lite App from the App Store. Follow the wizard to create a new virtual machine. Choose to “Install Windows or another OS from a DVD or image file”.

Click “Locate Manually” to manually select our HighSierra.iso file.

You may see a warning saying “Unable to detect operating system”. That is ok.

Click “Continue” and select “macOS” as the operating system.

The virtual machine should then boot to the installation iso.

Launch Terminal from the Utilities menu.

Format the virtual machine hard drive as HFS+ using the terminal. 

diskutil eraseDisk HFS+J MacHD disk0

Reboot the VM and it should boot to the installation iso again. Rebooting may be overkill, but I do it to ensure that the install iso is properly detecting the disk and partition layouts after the erase we just performed.

Again, launch Terminal from the Utilities menu.

We will use a special installer command called startosinstall, and manually run the installer from the iso rather than using the GUI.

The only flags needed are --converttoapfs NO to prevent converting the disk to APFS, and --volume /Volumes/MacHD to specify our target installation volume. 

/Volumes/Image\ Volume/Install\ macOS\ High\ Sierra.app/Contents/Resources/startosinstall \
	--converttoapfs NO \
	--volume /Volumes/MacHD