4.2.11   Create macOS Install Disk…

Once you’ve downloaded the macOS installer from the Mac App Store, this command helps you to create an installation disk. This makes it possible to re-install macOS, install it in a virtual machine, or install it on a different Mac without having to download it again. Additionally, if there are problems with a Mac’s hard drive, you may not be able to boot it and access the installer or recovery partition, but you will still be able to reinstall from the install disk that you create here. You can also use it as an emergency disk to boot a Mac and repair or reformat its hard drive, or to restore from a Time Machine backup.

When updating to a new version of macOS, it is recommended that you create your install disk before running the macOS installer, as the installer may delete itself (which would require you to download it again to create the install disk).

Preparing the Install Disk

• You can create an install disk using a spare hard drive, USB flash drive, or SD card. Just connect or insert the disk and make sure it shows up in the Finder. It should be formatted as Mac OS Extended in Disk Utility, not as APFS.
• You can also create an install disk image, for use with virtualization software or for later restoration to a disk. Use DropDMG’s New Blank Disk Image… command to create a disk image with Sparse Bundle for the image format, 15 GB (macOS Install Disk) for the volume size, and macOS Extended for the file system.

Creating the Install Disk

Choose Create macOS Install Disk from the File menu. DropDMG will ask you to select an installer (downloaded from the Mac App Store or Apple’s developer site) and then to select a destination volume. It will then erase the destination volume and use it to create a bootable install disk.

If the Install Disk Is Empty

In rare cases, the macOS Catalina installer will say that it successfully created the install disk but actually create an empty Install macOS Catalina volume. DropDMG includes a workaround to try to prevent this from happening, but if this occurs it should work if you simply choose the Create macOS Install Disk command again.

Downloading Older macOS Installers

When running macOS 10.15 or later, you can use the softwareupdate command in Terminal to download installers for previous macOS versions:

softwareupdate --fetch-full-installer --full-installer-version 10.14.6

You can then use the installer with DropDMG’s Create macOS Install Disk… command.

DropDMG From the Mac App Store

The Mac App Store version of DropDMG cannot create a bootable installer volume due to App Store limitations. However, you can still create one manually using the Terminal application:

1. Make sure that your destination volume is named Installer.

2. From the Finder’s Go menu, choose Utilities, then open the Terminal application.

3. Copy and paste these two commands into Terminal and press Return:

   • On macOS 10.14 and later, use:

     cd /Applications/Install\ macOS\ Ventura.app/Contents/Resources/
     sudo ./createinstallmedia --volume /Volumes/Installer/ --nointeraction
     

     You will need to change Monterey to a different name depending on the version of macOS that you are installing.

   • On earlier versions of macOS, use:

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

     You will need to change Sierra to a different name depending on the version of macOS that you are installing.

4. Enter your Mac’s admin password.