Globally handle WPF exceptions without a WPF Application object

Question

WPF provides a very convenient way to handle unexpected exceptions: I can just attach a handler to the Application.DispatcherUnhandledException event and all unhandled exceptions go this way:

Application.Current.DispatcherUnhandledException += (sender, e) => {
    // Show message, log exception, etc.
};

This works great for WPF application projects. Now, I have a library with WPF windows, which is called from a non-WPF application (it's a legacy VBA app, and the WPF library is made accessible via COM interop).

So, the thing is: I can create, open and show WPF windows (this works fine), but I don't have an Application instance. Application.Current is null. I use the WPF classes, but I operate them outside the WPF application framework.

Currently, the only drawback of this solution is that exceptions in WPF window event handler code are silently swallowed:

void Button_click(sender as object, e as RoutedEventArgs) {
    ...
    // some exception occurs here, but nobody hears her scream
    ...
}

I don't like that. I'd like to log them and show error messages.

My question: Is there a way to globally catch unhandled exceptions in this scenario or do I have to add a gerneric try-catch-log block to every WPF window event handler code I write?

What I have tried:

Attaching to AppDomain.CurrentDomain.UnhandledException. Doesn't work. Exceptions don't get there.
Reading the relevant parts of MSDN regarding WPF and Win32 interop (Ref 1, Ref 2, Ref 3). Exceptions are not mentioned there.

Heinzi Heinzi · Accepted Answer · 2012-05-30T10:21:21

Attach to the Dispatcher instead:

Dispatcher.CurrentDispatcher.DispatcherUnhandledException += (sender, e) => { 
    // Show message, log exception, etc. 
};

If no dispatcher exists yet, accessing CurrentDispatcher automatically creates a singleton Dispatcher which will also be used by the WPF windows.

Globally handle WPF exceptions without a WPF Application object

1 Answers