Cant install bootcamp in MBR after internal SSD upgrade I upgraded internal kSSD on my mac (MBP-2013) via Carbon Copy Cloner.

OSX loads fine, but for some reason I cannot boot into Windows that I have installed on external USB in MBR mode. Prior to changing the internal SSD the USB in MBR was booting fine. My 

I do need to have Windows installed via BIOS/MBR to use external GPU. I tried installing via Virtualbox and via unebootin, but have the same result - when I restart MBP to continue Windows installation I see a cursor for a second and then the screen goes blank. Not black as if it was turned off but blank - the display is clearly working but there is nothing being displayed.

My latest steps:


Format USB as MBR/Fat32
Get to final stages of Windows 10 Installer in Virtualbox
Reboot hold ALT -> pick Windows
Blank screen


What can I do to get Windows installation to continue in MBR mode? 

A note - if I format USB as GUID I can install and boot from USB windows just fine.
You could install rEFInd as by default this will automatically identify legacy Windows installations on internal or external disks.

Alternatively you could create a hybrid member on your internal SSD using gdisk and set at least one partition bootable. 

This will cause the firmware to initialize the BIOS/CSM/legacy support. 

You can pick any partitions as macOS will ignore it when booting.  If you have EFI, Macintosh HD and Recovery you could pick 2 and 3.  For example :


sudo gdisk /dev/disk0
take option r for recovery menu.
take option h to create hybrid member.  Here partitions 2 and 3 are chosen with 2 set bootable.


Type from one to three GPT partition numbers, separated by spaces, to be
added to the hybrid MBR, in sequence: 2 3
Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y

Creating entry for GPT partition #2 (MBR partition #2)
Enter an MBR hex code (default AF): AF
Set the bootable flag? (Y/N): Y

Creating entry for GPT partition #3 (MBR partition #3)
Enter an MBR hex code (default AF): AF
Set the bootable flag? (Y/N): N



take option w to write changes and exit.


Depending on your version of macOS you may need to disable SIP to use either gdisk or install rEFInd but you can enable it again after.