I've faced the error "This PC can't be upgraded to Windows 10" yesterday, and after spending some time debugging it, I've finally managed to update it.
In my case, Windows only displayed:
"Your PC has a driver or service that isn't ready for this version of Windows 10"
, but there was no clue as to what exactly was blocking the update: that was the cryptic issue, as no driver or service name actually appeared on the screen.
I've then created this video to show how you can possibly find the blocking cause: (as well as the fix, in my case)
Note: I've done this when updating to Windows 10 Version 2004 (20H1) (OS Build 19041.1), but it might also apply for future versions if the error message isn't improved, so we can at least find out the blocking driver/service.
@HotCakeXAs it's written in video's description, I was on Version 1909 (OS Build 18363.535).
That is, unless you're referring to my first enrollment of all time, which I'm afraid I can't answer this.