I have followed the steps in the apple support doc (above) to install Mojave onto an APFS partition on an external Seagate drive called Install macOS Mojave. The install appeared to go as it should have, but when the Mac rebooted, it booted into the Macintosh HD. In the newly formatted external drive, that got renamed Install macOS Mojave. An external drive that you can use as an installer for macOS Mojave is a good thing to have. If you have multiple Macs to upgrade, it’s quite easy to plug in the USB installer drive and run the installer than to log into the App Store, download the 6.02 GB OS installer, and then run it. If Mojave is installed on an external drive, eject/disconnect that drive. That choice to boot from Mojave will immediately disappear (right in front of your eyes!) Or, if you need to leave that drive connected, maybe because of another partition that you use, then simply erase that Mojave partition.
How to install macOS Mojave on external drive Hackintosh Step By Step Guide-. While retaining Catalina on the iMac, I want to install Mojave on the WD so that I can use software which is not Catalina-compatible. I am part of the way there. I have successfully created a bootable Mojave installer. It is on a flash drive which has changed its name to Install macOS Mojave.
These advanced steps are primarily for system administrators and others who are familiar with the command line. You don't need a bootable installer to upgrade macOS or reinstall macOS, but it can be useful when you want to install on multiple computers without downloading the installer each time.
MyVolumein these commands with the name of your volume.
* If your Mac is using macOS Sierra or earlier, include the
--applicationpath argument and installer path, similar to the way this is done in the command for El Capitan.
After typing the command:
Yto confirm that you want to erase the volume, then press Return. Terminal shows the progress as the volume is erased.
Determine whether you're using a Mac with Apple silicon, then follow the appropriate steps:
A bootable installer doesn't download macOS from the internet, but it does require an internet connection to get firmware and other information specific to the Mac model.
For information about the
createinstallmedia command and the arguments you can use with it, make sure that the macOS installer is in your Applications folder, then enter the appropriate path in Terminal: