I tried updating a few years ago. It would download the whole update, do the thing, reboot and rollback to Windows 10. No error message. Every single time, it redownload the whole thing. I tried it about thrice. And then I gave up.

The last time, checked something about clearing data because I figured maybe it was disk space. I didn't realize that meant delete everything including Documents and Downloads without confirmation. Th-thanks, Microsoft.