Cannot install macOS, because new account never linked to macOS. Will a bootable USB work?

Question

I have copied the title from this thread, because my case is very similar, but not quite the same with respect to one detail. Basically, I got a second-hand Mac Pro that was all set up by the previous owner. But I wanted to just erase and set it up anew, because of privacy concerns. Unfortunately, I did wipe the disk first from the recovery menu (Holding Cmd + R on bootup). So I cannot boot to the previous OS either. I used to have El Capitan on it.

The issue is I get the same message "This item is temporarily unavailable", because I have never owned a Mac so have no account linked to macOS. After much research, I thought logging in to iCloud from Safari would help, but it just gives me a white screen as mentioned in the linked question. So now I am considering 2 options:

1. Can I get a friend who does have a new Mac with a new version of the macOS (not El Capitan) to log in and then, once installed, remove him and login from my non-macOS-linked account?
2. There are quite lengthy steps to get a bootable USB with El Capitan from a Windows computer in this question. I don't mind following them, IF they work. Will this work or just give me the same problem because my account isn't linked to any macOS?

Answer 1

Note: The is this question: How can I download an older version of OS X/macOS?

I would consider using a Windows machine to create a bootable USB El Capitan installer to be a method of last resort. You can use your friends Mac to download El Capitan by using the link on this Apple webpage. Currently, this link is set to http://updates-http.cdn-apple.com/2019/cert/061-41424-20191024-218af9ec-cf50-4516-9011-228c78eda3d2/InstallMacOSX.dmg. You can create a bootable USB El Capitan installer by using the method given on this apple webpage. If this method fails to work, then you can try this answer.

I should point out that I have read where booting USB installers on some older Mac Pros may not be possible. For example, below are user Tetsujin's answers to questions regarding older Mac Pro computers.

• Latest OS X I can install on Mac Pro 3,1
• 2008 Mac Pro w/o Hard Drive - How do I install a new one?
• My Mac Pro 1,1 won't boot from any type of usb stick

Note: According to a comment posted Tetsujin, your Mac should be new enough to boot from USB.

---

How to Create a USB Flash Drive Mountain Lion Installer from OS X/macOS Recovery

1. Boot to OS X/macOS Recovery.

2. Use the Disk Utility Application to erase the volume where OS X/macOS is (or was) installed. When erasing, the choose the following.

   • Name: “Macintosh HD”
   • Format: “Mac OS Extended (Journaled)”

3. Initialize a 8 GB or larger USB flash drive. If using OS X Recovery (El Capitan or older), then use the the Disk Utility application to partition the flash drive. When partitioning, the choose the following.

   • Partition Layout: “1 Partition”
   • Name: “MyVolume”
   • Format: “Mac OS Extended (Journaled)”
   • Size: Keep the default value.
   • Partition Scheme: “GUID Partition Table”

   If using macOS Recovery (Sierra or newer), then use the Disk Utility application to erase the flash drive. When erasing, the choose the following.

   • Name: “MyVolume”
   • Format: “Mac OS Extended (Journaled)”
   • Scheme: “GUID Partition Map”

   When finished, quit the Disk Utility.

4. Open Safari by selecting “Get Help Online” (or similar link). Under Safari Preferences, change where downloaded files are saved to be the “Macintosh HD” volume

   Note: If a popup appears asking if Safari wants to use the “login” keychain, then select the “Cancel” button.

5. Use Safari to download the InstallMacOSX.dmg file for Mountain Lion from Apple. The link which will result in the file downloading can be found on any of the following webpages.

   • https://support.apple.com/HT211683
   • https://maclinks.publicvm.com
   • http://maclinks.publicvm.com

   You can also manually entering the URL, which will result in the file downloading. Currently this URL is https://updates.cdn-apple.com/2021/macos/031-0627-20210614-90D11F33-1A65-42DD-BBEA-E1D9F43A6B3F/InstallMacOSX.dmg.

   When finished downloading, quit Safari.

6. From the menu bar, select to open the Terminal application.

7. Enter the following commands.

   The command below will attach the InstallMacOSX.dmg disk image file as a device. This will automatically mount the volume “Install Mac OS X” stored in this disk image file.

   hdiutil attach /Volumes/Macintosh\ HD/InstallMacOSX.dmg
   

   The command below will expand the Mac OS X Installer flat package file InstallMacOSX.pkg into the new folder /Volumes/Macintosh\ HD/MacOSX.

   pkgutil --expand "/Volumes/Install Mac OS X/InstallMacOSX.pkg" /Volumes/Macintosh\ HD/MacOSX
   

   The command below will unmount the volume “Install Mac OS X” and then eject the device containing this volume.

   hdiutil detach "/Volumes/Install Mac OS X"
   

   The command below will attach the InstallESD.dmg disk image file as a device. This will automatically mount the volume “Mac OS X Install ESD” stored in this disk image file.

   hdiutil attach /Volumes/Macintosh\ HD/MacOSX/InstallMacOSX.pkg/InstallESD.dmg
   

   The command below will clone the source volume “Mac OS X Install ESD”. If prompted to erase contents, type Y to confirm that you want to erase the volume, then press return. The cloned volume should be named “Mac OS X Install ESD 1”.

   asr restore --source "/Volumes/Mac OS X Install ESD" --target "/Volumes/MyVolume" --erase
   

   The command below will unmount the source volume “Mac OS X Install ESD” and then eject the device containing this volume.

   hdiutil detach "/Volumes/Mac OS X Install ESD"
   

   The command below will rename the cloned volume “Mac OS X Install ESD 1” to “Install OS X Mountain Lion”.

   diskutil rename "/Volumes/Mac OS X Install ESD 1" "Install OS X Mountain Lion"
   

8. If you wish to install Mountain Lion on the current Mac, then select “Startup Disk” from the menu bar. Next, select the disk “Install OS X Mountain Lion” followed by the “Restart…” button. If necessary, confirm the restart.

   Otherwise, if you need to remove the USB flash drive, then enter the command below to unmount the cloned volume “Install OS X Mountain Lion” and then eject the flash drive containing this volume.

   diskutil eject "/Volumes/Install OS X Mountain Lion"