Here, I assume the ~/Downloads/pkg folder does not already exist. hdiutil attach ~/Downloads/InstallMacOSX.dmgĮnter the command below to extract folders and files from InstallMacOSX.dmg to the ~/Downloads/pkg folder. This will mount the readonly Mac OS Extended (HFS+) volume on /Volumes/Install Mac OS X. This was tested using macOS Catalina (10.15.7).įrom How to download macOS, download the InstallMacOSX.dmg file for OS X 10.8.5 (Mountain Lion) to your ~/Downloads folder.Įnter the command below to open InstallMacOSX.dmg. Update 2: How to Get the InstallESD.dmg File from Apple I was able to download this update on the host and transfer the update to the virtual machine where installation was successful. After installing, I was able to download and install all available updates except for an update to iTunes 12.14.3. I used the bootable installer to install Mount Lion in a VMware Fusion Player (Version 12.1.0) virtual machine. I did not need to use any third party tools (such as SuperDuper) to create the installer. I was able to create a Mountain Lion bootable installer from this downloaded file. I did download the InstallMacOSX.dmg file for OS X 10.8.5 (Mountain Lion) from How to download macOS on a iMac (21.5-inch, Late 2013) with macOS 10.15.7 (Catalina) installed. However, if you are still unable to install, perhaps you should include in your question the steps you used to create the installer.

Since you have stated you have correctly created the USB Mountain Lion installer, I will not post how to do so. You should choose 'Mac OS Extended (Journaled)' as the format. After booting from the Mountain Lion installer, you will need to open the Disk Utility and erase the entire internal drive. My 2011 iMac will boot without any issues.Ĭatalina uses APFS which will not be recognized by Mountain Lion. OS X 10.8.4 and I can not boot from any OS X 10.8.5 installer created using instructions given in this answer. However, shows the earliest OS X that can installed on my iMac (21.5-inch, Late 2013) is Therefore, you should be able to install Mountain Lion on your Mac. A quick check at shows the earliest OS X that can be installed on a 2012 MacBook Pro model is between OS X 10.7 3 and OS X 10.8.2 inclusively.

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