There can be very specific exceptions. In C# Winforms code I wrote, I have data loading code which I made async, called from UI code that was not. You need a ru

There can be very specific exceptions. In C# Winforms code I wrote, I have data loading code which I made async, called from UI code that was not. You need a running messageloop which was provided by a modal progress bar. Users could cancel the async code from the dialog. In the real world it is a quite a typical example where you want to call async code from non-async.