Can't create a bootable thumb drive to install macOS

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Level 1

8 points

Can't create a bootable thumb drive to install macOS

Hello Community,

on a Mac mini late-2014, I want to create a bootable thumb drive to install Big Sur. But the process fails. I follow instructions provide here Create a bootable installer for macOS - Apple Support

The command type in the console is

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia —volume /Volumes/InstBigSur

and I get this error

/Applications/Install macOS Big Sur.app does not appear to be a valid OS installer application.

Note that in the error message received, all the "\" are missing. Does that mean that the "\" are removed by Terminal before execution ?

I also tried creating a thumb drive to install Monterey and got the same issue.

Thanks,

Gilles Plante

Mac mini

Posted on Aug 16, 2023 9:04 AM

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Answer 1

Top-ranking reply

Planteg Author

Level 1

8 points

Aug 17, 2023 10:42 AM in response to Planteg

I solved the issue. I used a different way to crate the bootable thumb drive.

I used an App called Mist, see GitHub - ninxsoft/Mist: A Mac utility that automatically downloads macOS Firmwares / Installers.

This app automate the process completely. It provides access to :

- A list of Firmwares, you may download a specific one
- A list of Installers, you may download a specific installer or create a bootable Installer

I choose the option the create a bootable Installer. Next step is to select a volume formatted as Mac OS Extended (Journaled). If the drive is not formatted this way, there is a button to open Disk Utility !

Second step is to download the Installer.

Third step is to erase the bootable volume. That's when things went wrong. There was an error (-69888, 0) erasing the disk. Hum, my guess was that the thumb drive may be defective, so I used an 32G microSSD card instead. I started the process again.

Since the Installer has already been downloaded and parsed, that step was skipped. Erase the disk was completed and the bootable drive was successfully created.

The error message sent me in the wrong direction when doing the process in the terminal. It was not a matter of an invalid Installer application, it was a problem with the drive. Mist provided a much more explicit message and I was able to take action. Kudos to Mist creators.

I was able to install Big Sur on a MackBook Pro.

My guess is that createmediafile bash file has bug(s), I kindly ask Apple to have a look at that.

Thanks

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Answer 2

Aug 16, 2023 11:27 AM in response to Planteg

What is the size of the "Install macOS Big Sur.app"? If the downloaded installer is not about 12 GB in size, then it is the "stub" installer. You cannot make a bootable installer from the stub installer.

Other things to remember:

- Grant the Terminal enough access rights. Settings > Security & Privacy > Files and Folders > All On (seems to be enough), or > Full Disk Access then click on the + and locate Terminal.

- Use at least 16 GB not very old slow USB drive.

- USB drive might be needed to be plugged into the computer directly, not an USB hub (otherwise there might be a final generating "boot files" error).

- Format the USB drive as Mac OS Extended (GUID) on the same computer you prepare the installer (drive formatted on an Intel Mac might not boot Silicon Mac). I always let Disk Utility name it as "Untitled" so the following command for Big Sur should work:

sudo /Applications/Install\ macOS\ Big\ Sur.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled

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Answer 3

HWTech

Level 9

60,446 points

Aug 17, 2023 10:22 AM in response to Planteg

Try deleting the Big Sur & Monterey installer app and empty the Trash. Try downloading the Big Sur or Monterey installer again using the links in the Download section of the article you linked in your original post. Just make sure you end up with about a 12GB installer app.

You don't have any older copies of these installers anywhere else on this Mac do you? The reason I'm asking is that the App Store will end up downloading the installer to wherever another installer is found on the Mac. I learned this the hard way when it overwrote an older installer I had placed into another folder within my home user folder since I wanted to keep the old version (only discovered this when I couldn't find the new installer in the Applications folder).

As for the error message line showing the path without the escaped spaces "\", that is just how it normally prints the path when encountering an error. The error listed seems to imply that you have at least a significant portion of the installer since it did not report not being able to find the "createinstallmedia" utility within the installer's app bundle. The error message appears to imply a corrupt (or possibly incomplete) installer app bundle.

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