How to create a macOS 12 Monterey installer on an external drive
This tutorial goes through the process of creating an install drive from the newly released macOS 12 Monterey Beta application. Having an external drive allows you to install the operating system on multiple computers without re-downloading it, perform clean installations instead of booting from an existing operating system, and launch the built-in installer recovery for troubleshooting tools.
To get started, you will need the Install macOS 12 Beta app and a external storage drive of 16 GB or more. A USB stick is usually best for this, but you can also use an SD card (if your Mac has an SD card slot), a partition on a larger external hard drive, or another type of external storage drive.
Note– macOS Monterey is currently a beta version for developers only. A public beta will be released in the next month, which you can sign up for with Apple. This guide currently describes the process of creating the installer for the developer beta version and will be updated for the normal version of the Mac App Store in the future, when it becomes available. As usual, all beta testing is at your own risk.
Do not install beta operating systems on work-critical machines, especially without performing full backups first.
How to create a beta installer for macOS Monterey
1) Download a copy of the Install macOS 12 Beta request.
Users with a paid Apple Developer account you can download the Access utility beta from the Downloads section of your Apple Developer Account page. Once installed, open System preferences, software update to view and download the beta version.
Other users you will have to find a copy elsewhere. They can join the public beta for free, but they will have to wait longer for the beta versions. Public beta users will receive a slightly different version of the Beta access utility. Once installed, open System preferences, software update to view and download the beta version.
2) Once the download is complete, your Mac will launch the macOS 12 installer application. We don’t want to install it now, so close it, open your / Applications folder and locate the installer there. Do not rename or remove it from / Applications.
3) Format your drive> = 16GB to GUID Partition Map Y Mac OS Extended (Journaled) in Disk utility. This guide explains how, if you are not familiar with the method.
Note: All data on the external disk will be erased.
4) Name the newly formatted drive USB, for ease.
5) Then start the Terminal application and paste this command:
sudo / Applications / Install macOS 12 Beta.app/Contents/Resources/createinstallmedia –volume / Volumes / USB –nointeraction
- Remove “–nointeraction” from the command to ask for confirmation before erasing the external drive.
- The “–downloadassets” flag was introduced with macOS Mojave. Supposedly downloads assets on demand that may be required during installation. Presumably this is useful for offline installations, although I have never noticed any difference in online or offline installations when using it. I wouldn’t bother with that, but add it if you want.
- Previous versions of macOS used a “–applicationpath” flag in this command, but it is now deprecated and will fail if used. Use the command we provided above, instead of referring to the guides that were written for earlier versions of macOS.
6) press Pay in to issue the command and enter your password when prompted.
The terminal will provide a read of the external drive being erased and the installer files being copied to it. When Terminal declares that the drive has been created successfully, look for it on your desktop at Install macOS 12 Beta.
How to use the macOS 12 Monterey Beta installer
1) Shut down the computer where you want to install the beta version and insert the USB drive.
2) Turn on the computer while holding down Option (⌥).
3) The Boot Manager will display a list of boot drives. Please select Install macOS 12 Beta to boot from the installer.
4) Now you can proceed with the installation as you wish. The installer also allows you to reformat the connected drives and access tools such as Terminal, Startup Disk, and Firmware Password Utility.
Have fun trying the latest version of macOS from Apple! Remember: back up your data before upgrading to a new operating system, particularly a beta one.
Your drive can be used to troubleshoot your Mac if it becomes corrupted and unable to boot from its own recovery partition. Being able to reinstall your operating system or open a Terminal session from the external drive is also extremely helpful in a pinch. I mainly use these drives to install macOS on multiple computers without having to redownload the installer on each one, saving time and data.
If you need help with the guide, ask your question in the comments below!