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I've looked around at a number of the ReactiveUI samples, but I can't see a good simple example of how to handle exceptions, where a message should be displayed to the user. (If there is a good example can somebody point me to it?). My first question is how to handle an exception with ReactiveCommand and ToProperty. For example, I have the following code: public class MainWindowViewModel : ReactiveObject { public ReactiveCommand CalculateTheAnswer { get; set; } public MainWindowViewModel() { CalculateTheAnswer = new ReactiveCommand(); CalculateTheAnswer .SelectMany(_ => AnswerCalculator()) .ToProperty(this, x => x.TheAnswer); CalculateTheAnswer.ThrownExceptions .Select(exception => MessageBox.Show(exception.Message)); } private readonly ObservableAsPropertyHelper<int> _theAnswer; public int TheAnswer { get { return _theAnswer.Value; } } private static IObservable<int> AnswerCalculator() { var task = Task.Factory.StartNew(() => { throw new ApplicationException("Unable to calculate answer, because I don't know what the question is"); return 42; }); return task.ToObservable(); } } I think I must be misunderstanding ThrownExceptions, because this observable is not receiving any items when I run the code above. What am I doing wrong? My second question is how would I do this in a MVVM-friendly way. This blog entry mentions a User Errors feature, but I can't find any documentation on how to use it. How would I implement it into the above example? Edit : I've published an example solution <a href="https://github.com/wmaurer/ReactiveUI-Examples/tree/master/ReactiveUI-UserError" rel="n

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