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On my Early 2015 MacBook Pro (Monterey) I successfully created bootable Windows 10 on a partition on an external SSD using the method given in Answer 1 here:

Drivers not working on Windows 10 installed (CLI process) on external SSD running on MacBook Air 2018

I can boot into Windows 10 from this external SSD on my MacBook Pro (Monterey, latest) and a 2017 iMac (Ventura, latest) and all works fine (Windows adjusts to the new hardware).

However, on my 2018 Mac mini, Windows will not boot from this SSD. The Windows logo displays, an "attempting repair" message then displays, but then the display goes black, the Mac mini stays on, but nothing happens.

Interestingly, using the 2018 Mac mini, and using the same method, I successfully created bootable Windows 10 on an old HDD. It works OK, but is of course painfully slow.

So, on my Mac mini, I then tried installing Windows 10 on a new Samsung T7 SSD using the exact same method. However, the installation process fails to start. I see the Windows logo, which shows for about 90s, then nothing.

I subsequently tried another method using VirtualBox, but again, the the installation process fails to start. On booting to complete installation, the Windows logo shows for about 90s, then the display goes black and nothing happens, but the Mac mini stays on.

I have tried setting the Mac mini's Secure Boot to "no security" but it makes no difference. And "allow booting from external or removable media" is ON.

The Mac mini runs Windows 10 perfectly from Bootcamp on its internal SSD, but I wanted to run Windows from an external SSD as I'm running out of storage.

I tried another method using Rufus but again the Mac mini would not boot the installation, while the iMac did.

I cannot understand why the above method works on an old 2.5" HDD (in an Orico enclosure) but not a SSD, or why the mini cannot boot into Windows while my other Macs can.

I'm guessing it has something to do with the T2 chip?

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  • Please don’t add an answer the to the original question. Please add an actual answer so that you can mark it as “accepted.”
    – Allan
    May 19, 2023 at 1:36
  • Noted and thanks. May 19, 2023 at 23:20

1 Answer 1

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"Success" by accident.

I let the Windows 10 install process run on the SSD connected to my iMac, and that went smoothly. I then tried - for the very last time - to see if the SSD would boot into Windows from the Mac mini ... and this time it did! It now boots reliably into Windows.

I could not install the WindowsSupport drivers (downloaded from Bootcamp on the Mac mini) because (1) even running as Administrator via elevated CMD, BootCamp.msi is trapped in a loop (cannot install because another installer is running - although it is not), and (2) trying to install the drivers manually via Device Manager results in a "cannot install" error after a very long wait. However, after some time - half an hour or more - Windows seems to have installed various drivers, so sound now works as does Bluetooth.

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  • Update: Note that my Mac mini will only boot into Windows on the external SSD if no other HDD or SSD drives are plugged in. If they are, the boot hangs at "Preparing startup repair". Jun 5, 2023 at 2:58
  • Final Update: if external drives (in my case APFS encrypted format) are plugged in AFTER Windows 10 boots, then on subsequent boots with those devices plugged in, Windows boots as per usual. Jun 18, 2023 at 5:27

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