BCDEdit /enum : "The boot configuration data store could not be opened"

Hi all,

I upgraded Win7 to Win10 and had to use an usb thumb in between as boot partition for reasons I cannot track back now.

Whenever I try to update Win10 I get the error 0x800f0922. I was unable to determine what happens, but since it only affects big system patches like "cummulative" or large .NET updates I suspect the borked BCD setup might a part in that.

I tried various things like clearing the update cache, applying the patches manually and about everything I could find on the net, but nothing helped, thus I assume the issue to be more general.

In short, to narrow this down I'd like that fixed but not sure how. The Win10 system does boot, though. Hints appreciated.