I'm shipping a project which my client (the army) wants to run on new MacMinis2019, which they, being less tech saavy consider a whole (the mac with all the software and configuration installed on it is the product).

These machines are deployed in "Internet-free" zones entirely cut from the internet in order to avoid possible leakages of sensible data.

As part of the many procedures they wish to have access to, one of them is to clone one of the macs onto another one which may be presenting behavioural defects in the software, or whatever... it's no longer doing what they want and the quick and easy fix for them is or rather used to be (with old 32bit MacMinis) to clone a "working" one onto a "broken" one in order to have them all work once again.

I'm having trouble holding up this part of the bargain with the new Macs especially given the no internet constraint.

Here's what I've tried.

I plug in a thunderbolt cable between the two macs, I boot the broken one holding T so it has the thunderbolt logo on screen.

then I boot into the other normally and install and run Carbon Copy which I then use to clone.

The process is error-free and I even sometimes reboot the affected machine to a sucess... once and then on the new reboot it shows me the question mark logo.

sometimes I get this straight away.

I try rebooting holding R to access the disk utility and run First Aid. I then try to select a startup disk from the apple main menu and select the Hard Drive and click "Restart..." but I get a message saying :

You can't change the startup disk to the selected disk.

An internet connection is required to update this startup disk. Check the network connection and try again or select another startup disk.

As I explained above resorting to connecting to the internet is utterly unacceptable for my client.

Why is this happening? is there a better way to clone? is there a command line to type or some other solution to not be prompted for internet connection?

  • You'll need a test lab where you work on this in my experience - cutting off a Mac from the internet but having it on a network means you'll deprive yourself of Xprotect / updates / patches / firmware that only comes when you allow traffic from and to Apple's IP address block - I understand your goals and hope that we can help in some narrow cases. Any reason why you tagged CCC?
    – bmike
    Commented Jul 10, 2019 at 13:47
  • @bmike mentioned this tool in my post. it's how I clone the macs. My superiors told me the client does not care at all about the "security risks" of working offline since they hermetically seal the building from viruses by scanning any ingoing or outgoing media with computers that are themselves up to date. In any event the no internet thing is final and they don't care about any of these concerns. (I am in said test lab. I am using another linux laptop to write these posts but the macs themselves are not plugged into the internet)
    – tatsu
    Commented Jul 10, 2019 at 14:11
  • Good luck! Sounds like you are going to run with the plan you have. I see you are realizing that the installer is designed to contact the servers to validate that the install image is valid.
    – bmike
    Commented Jul 10, 2019 at 14:31

1 Answer 1


I'm assuming you've disabled SecureBoot, and that the volume name is identical in what follows:

It's possible that the T2 chip on these new (2018) Minis makes 'straight' cloning difficult. I had the same problem when I cloned my old 2012 Mini's volume onto my 2018 Mini : I too got a flashing question mark. I was able to fix it by installing Mojave on top of the newly cloned disk. I used a USB install media (after disabling SecureBoot!). The disk booted perfectly after that, with all my files still in place.

I tried blessing the startup volume (though I may not have used the correct commands); and resetting NVRAM, without luck. I can only assume that the T2 chip 'knows' something has been changed and it requires an Apple installer to reset.

It may be possible to perform the 'reset' without having to do an entire OS install, but I don't know what the procedure might be.

  • wait I don't want to keep files and folders, I want to keep programs and their complex setup and configuration. I want a full clone. just making sure we're on the same page here. sounds like you're suggesting a way to obtain a fresh Mojave or add a fresh Mojave to the boot options but that wounldn't accomplish what I want.
    – tatsu
    Commented Jul 10, 2019 at 13:39
  • another thing I want to point out is reinstalling the OS used to be possible for me from the restore options on the mac. now the option is there but also gives me an error message about internet. what could have changed that makes it ask me for internet at every turn?
    – tatsu
    Commented Jul 10, 2019 at 14:08
  • 1
    @tasu No: I cloned my disk, and to make that clone bootable, I had to reinstall the OS. A default reinstall maintains all the other files, apps and user accounts in place.
    – benwiggy
    Commented Jul 10, 2019 at 14:33
  • 1
    @tatsuOne other thing: it's possible that you are only getting the Internet Recovery option because the Recovery Partition has been wiped in the cloning process.
    – benwiggy
    Commented Jul 10, 2019 at 14:33
  • 1
    @tatsu Exactly - you'll need to have an image that - you'll then have to have a process to scan / quarantine / validate your image before you connect it to the offline machines. in the past, we had luck with ASR to clone a machine - you could validate that as well, but making your trusted installer might be more effective in your case.
    – bmike
    Commented Jul 10, 2019 at 15:17

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