Visual studio used to have a specific checkbox to \"Break on Un-handled exception\". In 2015 this has been removed (or moved somewhere I cannot find it). So now my convert
There's definitely some bug in Visual Studio that can cause it to get stuck requiring a restart. Even VS2015.
I had a single threaded situation where a NullReferenceException was getting caught by an 'outer' handler (still in my code) even though I asked for it to break when it was raised.
I realize this is a 'handled' exception and you're talking an 'unhandled' one - however I'm pretty sure that sometimes a quick restart of VS will fix this, if IISRESET doesn't.