This post is a note to myself – after upgrading Xcode to 9.4 I found that Visual Studio for the Mac seemed to fail to run on the iOS simulator, instead what happens when you run the VS is that it simply stops, no errors are shown, nothing.

What to do after upgrading Xcode

After upgrading/updating Xcode, always run Xcode to allow it to install any updates. Part of the upgrade might be that the Visual Studio for Mac has updated the simulator, in my case this is what had happened. Xcode 9.4 had the 11.4 version simulator whereas Visual Studio for Mac listed version 11.3.

Running Xcode installed pending updates but I also needed to go to the Xcode Preferences and in the accounts tab, ensure I was signed in (if the login has expired).

Now Visual Studio for Mac displayed the correct versions of the simulator and all worked again.