UE4.17 will not compile with new studio2017_15.3 update

This worked for me. If you’re on Windows 10, you probably don’t need the Windows 8.1 SDK.

Edit:
Just a follow-up to this. I didn’t need the 8.1 SDK on a freshly installed Windows 10 PC, but it was required on a PC that had been upgraded from 8.1 to 10. On both computers, I was able to compile after making these changes.