External Boot Camp partition doesn't show up in Startup Manager


I have created an Winclone image from an internal Boot Camp partition and have restored that image to an external exFAT hard drive partition following this guide, except for that I have not used Sysprep. Now, I want to boot to that external partition, however, when I boot into the Startup Manager pressing the Alt key during startup, I don’t see the created external Boot Camp partition in the list. I have also enabled booting from external media in the Startup Security Utility but with no effect.

Could you please help me make the external Boot Camp partition show up in the Startup Manager so that I can boot into it? I am using Winclone 7.3.2 with macOS Mojave 10.14.5 on a 13-inch MacBook Air 2018. The Boot Camp partition runs Windows 10 (1809 update). The external drive is connected via USB-C to USB-A adapter.

Thanks in advance.


Regardless of anything else, it should definitely show up when holding down the option key. We have tested the 2018 MacBook Air (T2) with a USB-C drive and windows 1809 and it does boot externally for us. All the files that make it boot are on the EFI partition. Can you try and mount the EFI partition on the external drive and see if the Windows boot files are there? For example, if the external drive is /dev/disk1, mount efi by running:

sudo diskutil mount /dev/disk1s1

Then an EFI volume should mount on your desktop.


Hello Tim,

thanks for the suggestion. I’ve tried mounting the EFI partition according to your instructions and it succeeded and I’ve been able to locate the “Boot” folder there.

Meanwhile I have upgraded to macOS Catalina, but the external Boot Camp partition still doesn’t show up in the Startup Manager. The only partitions I see there are “Macintosh HD”, Boot Camp (the internal one) and the "“EFI Boot” partition…

Do you have mor suggestions what to try to be able to boot into the external Boot Camp partition?

Since I’ve upgraded to Catalina, I can no longer use WinClone 7, therefore, I am considering to buy WinClone 8. But if I am not able to boot into the external Boot Camp partition using WinClone 8, I will have to ask for a refund.

Thanks and kind regards.


I doubt Winclone 8 will change the result, but you can try and we can refund if it doesn’t work. I have considered dropping support for external drives, but it does work well for some folks and is very nice when it does work. It is very dependent on hardware, Windows, and the connected bus it is very difficult to say definitely if it will work or not prior to trying.

Upgrading to Winclone 8 didn’t solve the issue. However, I decided not to ask for the refund because I still want to use Winclone for a restoration of an internal volume.

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