Possible to Make Mountain Lion USB Installer from Apple.com Download?

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Possible to Make Mountain Lion USB Installer from Apple.com Download?

Hello All,

I have a 2008 Mac Pro that recently had its hard drive replaced due to failure. I do not have a TimeMachine back up as this is a computer for very mundane tasks. Is it possible to create a USB installer using the Apple.com version of the Mountain Lion download?

https://support.apple.com/kb/DL2076?locale=en_US

I have tried to using Terminal and Disk Creator. However, both output an error message that the download from Apples website is lacking the "Contents/Resources/createinstallmedia" file.

I am trying to create the USB installer using a machine running macOS Catalina 10.15.7. I also have access to a Windows 10 machine.

Any help or insight would be greatly appreciated. Thank you!!

Posted on Jul 7, 2021 12:44 PM

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Answer 1

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midnightsvt Author

Level 1

8 points

Jul 8, 2021 9:56 AM in response to HWTech

@HWTech - Thank you for the reply.

I ended up following this tutorial on YouTube using a Windows 10 PC.

https://www.youtube.com/watch?v=hM1rpZtdzU8

This seemed to work. I was able to hold the "Option" key on start and select the install USB. I then followed the prompts to install Mountain Lion on the internal hard drive. I watched as the macOS installation proceed and was given a "Install Succeeded" message followed by a restart.

However, on the startup (after the auto restart), the Mac Pro goes back to the Recovery Screen and never loads Mountain Lion. Is this a product of a bad USB installer or something else?

EDIT: I just reset the NVRAM / PRAM and now the machine is booting into the Mountain Lion OS.

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Answer 2

HWTech

Level 9

60,554 points

Jul 7, 2021 6:26 PM in response to midnightsvt

In the Finder Right-click the "Install macOS Mountain Lion" app and select an item called "Show Package Contents". Navigate the folders to "Install macOS Mountain Lion/Contents/Resources" to see if the file "createinstallmedia" exists. If it does exist, then drag & drop it onto an open Terminal window to autocomplete the path. Mistyping the path is the most common error users make. Just make sure to first type "sudo " with at least one space after "sudo" before dragging & dropping the "createinstallmedia" file onto the open Terminal Window. You can do something similar to auto fill the path to the "Install macOS Mountain Lion.app".

Also make sure to follow the instructions for creating a macOS 10.11 USB installer.

I have not yet downloaded or tried to make a bootable macOS 10.8 USB installer from the new download Apple just released. If you still have problems, then copy & paste the command and error message into the "Code Insertion" tool here whose icon looks like "<>". Or take a screenshot of the Terminal window.

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Possible to Make Mountain Lion USB Installer from Apple.com Download?

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