I “lost” my optical drives. I had to mess with a registry key to get them back.
Here’s one I didn’t realize until I went to play Civ 5 and my saves were all gone. Because I have my main OS on a small SSD (and originally had my games on a regular hard drive – now they’re on their own bigger SSD), I had My Docs and My Pictures pointing to another drive. The Windows 10 upgrade lost those settings. I had to open up Windows Explorer and right click on each of those and change the location on the location tab.