<Application xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="WpfApplication1.App" StartupUri="MainWindow.xaml" DispatcherUnhandledException="App_DispatcherUnhandledException" /> //File:Window.xaml.cs using System; using System.Text; using System.Windows; using System.Windows.Threading; namespace WpfApplication1 { public partial class App : Application { void App_DispatcherUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs e) { StringBuilder sb = new StringBuilder(); sb.AppendFormat("{0} ", e.Exception.InnerException.Message); sb.AppendFormat("{0} ", e.Exception.Message); sb.AppendFormat("Exception handled on main UI thread {0}.", e.Dispatcher.Thread.ManagedThreadId); MessageBox.Show(sb.ToString()); e.Handled = true; } } }