New
#31
Probably the optional upgrade does some changes to the system that are incompatible with some specific devices such as old Realtek HD audio cards, and you cannot access any audio or video device (I mean TV tuner etc, not VGA). I will not install it just in case.
Meanwhile I upgraded successfully from v2004 to v21H1 and created a restore point, just in case. I will update every application and then create a full backup with Acronis or Macrium. I want next time I need it (I hope never) to have all my current data so I would miss very little restoring it.