Depending at which point you interrupted the update, the potential for system damage remains. In these cases we might usually refer you to a tutorial such as this one:
You are no doubt aware that Manjaro does not support Microsoft’s implementation of Secure Boot, and disabling it is the best resolve.
As to your error, my best guess is: 
Manjaro has no capability of enabling or disabling Secure Boot; some Windows versions apparently do.
If you’re multi-booting, I might give Windows (11?) the evil eye. Otherwise, cosmic rays, maybe?!
Regards.