That's the Microsoft update, we all got it, so you should make a restore point and install it.
To be clear, .NET 3.5 is not a discretionary user downlad for Windows 10. Reason: because it came pre-installed.
Since Vegas 18 does not use 3.5, it will be transparent. I've only seen sporadic reports of problems with the 4.8 update. Calling the render dialog in VP14 seems a bit slower, but of course I can't be sure.
I had to do a windows update to be able to reenable that .NET 3.5. But finally its done.
Still no image sequence export option visible. i don't have a Vegas 17 available to "fire up" as the user mention in the adjoined thread. This is getting annoying to have options appear and disappear like that. Somebody in the programming team should be taking it seriously.