"Setup has detected that Visual Studio 2015 Update 3 may not be completely installed...."

"...Please repair Visual Studio 2015 Update 3, then install this product again."

I'm getting this when I try and update the ASP.NET Web Tools Extension in my version of VS 2015 which I installed only today. After I got this error I checked and my version was Update 3. I tried to install it regardless and got a message saying that I already had it.

Any ideas on how I can get around this issue?

Why is Visual Studio installer not installing?

Please go to Windows Update, ensure that all recommended Windows Updates are installed and completed, then reboot your PC. (Open Windows Settings ( Windows + I ) -> Go to Update & Security > Troubleshoot.

Ok after some digging I got to the bottom of this. It seems that I need to have .Net Core Installed. However when I go to install that I get the same error. The workaround is to run the downloaded .exe from the command line with the added parameter: