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How do I create a bootable USB from the InstallMacOSX.dmg file downloaded from Apple's support page (https://support.apple.com/en-us/HT208969) ?
I'm trying to create a bootable USB for macOS High Sierra in order to install on a late 2009 iMac. I am currently running macOS Catalina on my 2019 iMac.
Thank you!
iMac 21.5″, macOS 10.15
Oh dear you need to open the InstallMacOSX.dmg (double-click on it) it will open to the InstallMacOSX.pkg.
Double-click on the InstallMacOSX.pkg and an installation window will open, this does not install El Capitan
but creates the Install OS X El Capitan.app in your Downloads folder. Use that to create the bootable USB.
One thing to note is that in order for the creation of the Install OS X El Capitan.app to work you must perform the procedure from InstallMacOSX.pkg to Install OS X El Capitan.app on a mac that is either running El Capitan or was/ is capable of running
El Capitan. Therefore if you try this on a mac that came preinstalled with an OS newer than El Capitan you will get an error.
Oh dear you need to open the InstallMacOSX.dmg (double-click on it) it will open to the InstallMacOSX.pkg.
Double-click on the InstallMacOSX.pkg and an installation window will open, this does not install El Capitan
but creates the Install OS X El Capitan.app in your Downloads folder. Use that to create the bootable USB.
One thing to note is that in order for the creation of the Install OS X El Capitan.app to work you must perform the procedure from InstallMacOSX.pkg to Install OS X El Capitan.app on a mac that is either running El Capitan or was/ is capable of running
El Capitan. Therefore if you try this on a mac that came preinstalled with an OS newer than El Capitan you will get an error.
That doesn't work because I don't have the Install OS X El Capitan.app, only the InstallMacOSX.dmg that is downloadable from the Apple support site mentioned before.
Install MacOSX.dmg contains the files to install Mac OS X El Capitan. Do you want to install El Capitan.
If you want to download High Sierra then your link connects you to the App Store High Sierra page
it should say Get or Download, this will download the Install macOS High Sierra.app to your Downloads folder.
Follow the link in Dialabrains reply to create a bootable USB installer.
bmsewell wrote:
I'm trying to create a bootable USB for macOS High Sierra in order to install on a late 2009 iMac. I am currently running macOS Catalina on my 2019 iMac.
Maybe I read your post incorrectly.
My bad, I did mean El Capitan. Yeah, since I'm running Catalina, I get this error when trying to run the pkg file:
You've lost me. I thought you were trying to create a High Sierra bootable USB installer. It downloads as an app. El Capitan downloads as a dmg file.
Yep you need to do this on a mac that is capable of running El Capitan, as I said earlier.
Yep. What Eau Rouge said.
You need access to a 2015 Mac or earlier.
Bootable USB from "InstallMacOSX.dmg"
