(...)
This is beyond ridiculous that I will have to install Windows 10 from scratch and spend days to reinstall everything as it runs today.
(...)
PS. I did all the magic advised in this thread ( except media creation ) , but no avail.
It didn't take days, only a couple of hours. I was having dinner and watching Netflix and only would check back with my computer once in a while to click a button. As I wasn't patient enough to wait for it to finish before I went to bed I left it on over night, and this morning everything worked perfectly.
I am relieved, really. Had this issue since the August update, too, which was the first ever to fail installing. But from here on out I hope that won't happen again.