How can I override the default uncaught exception dialog?

Question

When an exception goes uncaught in a .NET app, the virtual machine displays an error message to the user. I'd like to be able to display my own error message, without having to put a catch block at the top level of my app (because that makes debugging uncaught exceptions more tedious).

Right now I display my own error dialog in an AppDomain.UnhandledException event listener, but the .NET-created dialog still shows up. I'd also like to avoid Environment.FailFast as that would bypass my finally blocks (to which I'm still somewhat attached).

That's a feature of the JIT. I'm not sure that there is a way to modify it... — Chris Laplante, Jul 04 '12 at 20:37
I'd probably create a production mode / development mode configuration variable to switch between viewing your own dialog (and catching) in the top level and not viewing it. It's also a good idea in general for debugging... — Benjamin Gruenbaum, Jul 04 '12 at 20:45
It is definitely possible, I remembered Red Gate has done something in this field. See this [image](http://www.red-gate.com/products/dotnet-development/smartassembly/assets/images/error_reporting_dialog.png) and the related product [page](http://www.red-gate.com/products/dotnet-development/smartassembly/learn-more/screenshots). I am not sure if they have a free version, but they have done this, so there must be a way! — oleksii, Jul 04 '12 at 20:54
possible duplicate of [What's the difference between Application.ThreadException and AppDomain.CurrentDomain.UnhandledException?](http://stackoverflow.com/questions/2014562/whats-the-difference-between-application-threadexception-and-appdomain-currentd) — Hans Passant, Jul 04 '12 at 21:03

score 5 · Accepted Answer · edited May 23 '17 at 10:30

5

If this is WinForms, you have to handle AppDomain.UnhandledException and Application.ThreadException to catch them all. Some exceptions filter into one and others into the other.

There was a similar (but not exact duplicate) question here that should help: C# - WinForms - Exception Handling for Events

edited May 23 '17 at 10:30

Community

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answered Jul 04 '12 at 20:51

David

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score 1 · Answer 2 · edited Aug 13 '12 at 14:50

Windows Forms has a built-in exception handler that by default catches an unhandled managed exception when no debugger is attached, and the exception occurs during window message processing, and jitDebugging = false in App.Config. It then shows a dialog to the end-user and prevents app termination.

You can change the registry setting DbgJitDebugLaunchSetting under HKLM\Software\Microsoft\.NetFramework. This has one of three values of which I'm aware:

0: shows user dialog asking "debug or terminate".
1: lets exception through for CLR to deal with.
2: launches debugger specified in DbgManagedDebugger registry key.

In Visual Studio, go to Tools > Options > Debugging > JIT to set this key to 0 or 2. But a value of 1 is usually what you want on an end-user's machine

(See http://msdn.microsoft.com/en-us/library/2ac5yxx6(v=vs.90).aspx)

score 0 · Answer 3 · answered Jul 04 '12 at 20:45

0

How about a similar pattern that is in WP7?

    // Code to execute on Unhandled Exceptions
    private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
    {
        // do stuff
        if (System.Diagnostics.Debugger.IsAttached)
        {
            // An unhandled exception has occurred; break into the debugger
            System.Diagnostics.Debugger.Break();
        }
    }

answered Jul 04 '12 at 20:45

Lukasz Madon

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I'm not sure how this lets me display a custom message. – zneak Jul 04 '12 at 21:02

How can I override the default uncaught exception dialog?

3 Answers3