To rule out a bad administrator permission issue on your current windows account, try creating a new windows admin account for testing. Takes a couple of minutes and won’t mess with anything on your current admin account.
Outside of that and without more specific information the only other thing I can suggest is to clean up the Blizzard app. Since the issue is the app is not able to do a task it needs to do with applying data to itself or the affected game client, it could corrupt app data in regards to the affected client. This will not remove the game clients just settings for how the app interacts with them.
- Open file explorer/file manager (Right Click Windows Start)
- Navigate to the folder where the desktop application would normally be installed. Delete that folder if it exists (usually program files x86)
- Type the following into the address bar (not the search bar): %APPDATA% and press enter.
- Delete the Bnet and blizzard folders inside the appdata folder if they exist.
- Repeat steps 3 and 4 with %PROGRAMDATA% %LOCALAPPDATA% and %TEMP%
- Empty the recycle bin.
- Now reinstall the app to the C: Drive.
We recommend the C drive for the Blizzard app because of potential windows permission issues with programs that can modify other programs. Your games should be fine on the D drive.
That should help but if the issue persists, I’d suggest submitting a support ticket for additional assistance:
https://us.battle.net/support/en/help/contact/159/ticket
Please include the requested system files and also any steps you tried.