Especially during in place upgrades I ran several times into installation errors.
“Windows installation encountered an unkown error and cannot continue.”
The reason at the moment seems to be the (177kb) update the setup assistant is recommending.
If you leave the option unchecked the installation will run through.
I ran also into errors during a normal setup on a blank disc with the same error but couldn’t get a hint why.
Maybe it was a corrupt iso image.