Here’s how to fix it:
You will need Windows 10 Setup media to recover the WinRE.wim, if you don’t have this you can user
To avoid the need for extra partitions, I used a folder c:\recovery
mount your setup media (iso or usb)
in an elevated prompt run the following commands:
creating folders
md c:\recovery
md c:\recovery\mount
** mounting Windows Image from media
** (if setup media drive letter is not e: replace the e:\ with the correct driveletter)
dism /mount-wim /wimfile:e:\sources\install.wim /index:1 /mountdir:c:\recovery\mount /readonly
** Copying WinRE.wim from image
copy “C:\Recovery\mount\Windows\System32\Recovery\Winre.wim” c:\recovery\
** Unmounting Image
dism /unmount-wim /mountdir:c:\recovery\mount /discard
** Enable WinRE
reagentc /SetReImage /Path c:\recovery\winre.wim /index 1
reagnetc /enable
reagentc /info
** The last command should show RE enabled, after this I was able to successfully run MBR2GPT
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