creating bootable installer on a thumb drive failed
I am in the process of upgrading my late 2013 27" iMac from High Sierra to Mojave. I am trying to follow Dave and John's advice by creating a bootable copy of my HD using Carbon Copy Cloner as well as making a bootable installer thumb drive.
I successfully created the bootable copy of my HD. However my attempt to create a bootable installer thumb drive using a terminal command failed.
I downloaded the High Sierra installer from the Mac App Store and followed the instructions on this support.apple page on How to Create a Bootable Installer for macOS.
After entering the recommended terminal command a message came back that the "Sierra.app does not appear to be a valid OS installer application"
I entered the following command:
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/thumbs --application /Applications/Install\ macOS\ High\ Sierra.app
I received the following response telling me the installer is not a valid application:
/Applications/Install macOS High Sierra.app does not appear to be a valid OS installer application.
Where have I gone wrong? How can an application downloaded directly from Apple be not valid?
From what you've pasted you have a typo in the last part where the parameter should be "applicationpath" not "application". Eg.
sudo /Applications/Install\ macOS\ High\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install\ macOS\ High\ Sierra.app
I always refer to the Macworld site as they issue updated instructions each year for this task including links to apps that will do it for you from a GUI interface: https://www.macworld.com/article/3204672/macs/how-to-create-a-bootable-macos-high-sierra-installer-drive.html
Just tried it again with terminal and with one of those GUI apps (Install Disk Creator) and I am getting the same error message that the installer downloaded from Apple is not valid:
The selected item does not appear to be a valid macOS Installer.
It is lacking the file "Contents/SharedSupport/InstallESD.dmg"