In my App() initialization code, I include a generic handler
UnhandledException += Application_UnhandledException;
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
Debugger.Break();
}
I have 2 screens that work fine, but when navigating quickly back and forth between the two screens a number of times (varies between 7 and 12) I hit this breakpoint with the exception
{System.Windows.ApplicationUnhandledExceptionEventArgs} base {System.EventArgs}: {System.Windows.ApplicationUnhandledExceptionEventArgs}
ExceptionObject: {System.ArgumentException: Value does not fall within the expected range.}
Handled: false
and if I remove the UnhandledException and set the Debugger to break on unhandled, I get the following:
Unhandled Error in Silverlight Application
Code: 4004
Category: ManagedRuntimeError
Message: System.Windows.Markup.XamlParseException: 2028 An error has occurred. [Line: 0 Position: 0] ---> System.ArgumentException: [Arg_ArgumentException]
Arguments: Debugging resource strings are unavailable.
Often the key and arguments provide sufficient information to diagnose the problem.
See http://go.microsoft.com/fwlink/?linkid=106663&Version=4.0.60531.0&File=mscorlib.dll&Key=Arg_ArgumentException
at MS.Internal.XcpImports.CheckHResult(UInt32 hr)
at MS.Internal.XcpImports.Collection_AddValue[T](PresentationFrameworkCollection`1 collection
even if I set e.handled = true, my application crashes.
Important Note:
The application, under a MVVM framework works over 99.9% of the time, navigating between dozens of screens. Only one user has reported being able to crash the application by quickly navigating between two screens, and then only after about 10 back and forth tries
My questions are:
Any way to determine what is causing it?
Any way to prevent it?
What is the best way to recover from this error?
Followup:
The problem was solved by naming the view control, even though that should not be needed
from
<telnav:RadTabItem.Content>
<views:Detail_InfoView />
</telnav:RadTabItem.Content>
to
<telnav:RadTabItem.Content>
<views:Detail_InfoView x:Name="DetailsInnerView"/>
</telnav:RadTabItem.Content>
Related
I have a WPF application that consists of multiple projects that have forms, classes, base classes, etc..
Because of the large code base I want to make sure if an exception does happen I can catch it, notify the user and let the application continue without crashing. I understand the pros and cons to doing this.
In the App.xaml.cs of the application I have:
private void OnApplicationStartup(object sender, StartupEventArgs e)
{
Application.Current.DispatcherUnhandledException += CurrentOnDispatcherUnhandledException;
AppDomain.CurrentDomain.UnhandledException += CurrentDomainOnUnhandledException;
Dispatcher.UnhandledException += DispatcherOnUnhandledException;
UI.Views.Windows.MainWindow.Show();
}
private void DispatcherOnUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs dispatcherUnhandledExceptionEventArgs)
{
MessageBox.Show("TEST 3");
}
private void CurrentDomainOnUnhandledException(object sender, UnhandledExceptionEventArgs unhandledExceptionEventArgs)
{
MessageBox.Show("TEST 2");
}
private void CurrentOnDispatcherUnhandledException(object sender, DispatcherUnhandledExceptionEventArgs dispatcherUnhandledExceptionEventArgs)
{
MessageBox.Show("TEST 1");
}
If an exception happens anywhere those messages boxes are shown which is great, the problem is right after it shows the message the application still crashes. If I run the application in debug, Visual Studio will jump to the place were the exception happened and if I continue it will then go to the message box.
I think the problem has something to do with that but I am not sure. Is there a way to catch the exception like I am above but at the same time not have the application crash after?
Thank You
EDIT
The exceptions that get through to the UnhandledException section will be things like NullReference, NotSupported or Database Exceptions for the most park. If a "serious" exception gets cought like Stack Overflow I will simple notify the user and kill the app. I still need to find a way to stop the app from crashing on non serious exceptions though.
I think you need to set
dispatcherUnhandledExceptionEventArgs.Handled = true;
What kind of exception is your application catching? Using UnhandledException for exceptions that change state will not work unless you are setting HandleProcessCorruptedStateExceptionsAttribute attribute.
From MSDN documentation:
AppDomain.UnhandledException Event
Starting with the .NET Framework 4, this event is not raised for exceptions that corrupt the state of the process, such as stack overflows or access violations, unless the event handler is security-critical and has the HandleProcessCorruptedStateExceptionsAttribute attribute.
http://msdn.microsoft.com/en-us/library/system.appdomain.unhandledexception.aspx
I'm working with a Silverlight 4 application and we use Prism/MEF to build modules.
Each module is created as a Silverlight application. We then use a ModulesCatalog.xaml file to control how the modules are loaded.
We had 6 modules and everything was working perfect.
This week we're adding a 7th module and we just have the new Silverlight application created. We setup the module class as follows.
[ModuleExport(typeof(InsightModule))]
public class InsightModule : IModule
{
}
Then we added an entry to our ModulesCatalog file.
Now when we run the application we start getting all types of recomposition errors. The stack shows this.
at System.ComponentModel.Composition.CompositionResult.ThrowOnErrors(AtomicComposition atomicComposition)
at System.ComponentModel.Composition.Hosting.ExportProvider.OnExportsChanging(ExportsChangeEventArgs e)
at System.ComponentModel.Composition.Hosting.CatalogExportProvider.OnCatalogChanging(Object sender, ComposablePartCatalogChangeEventArgs e)
at System.ComponentModel.Composition.Hosting.ComposablePartCatalogCollection.OnChanging(Object sender, ComposablePartCatalogChangeEventArgs e)
at System.ComponentModel.Composition.Hosting.AggregateCatalog.OnChanging(ComposablePartCatalogChangeEventArgs e)
at System.ComponentModel.Composition.Hosting.ComposablePartCatalogCollection.RaiseChangingEvent(Lazy`1 addedDefinitions, Lazy`1 removedDefinitions, AtomicComposition atomicComposition)
at System.ComponentModel.Composition.Hosting.ComposablePartCatalogCollection.Add(ComposablePartCatalog item)
at Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleInitializer.CreateModule(ModuleInfo moduleInfo)
at Microsoft.Practices.Prism.Modularity.ModuleInitializer.Initialize(ModuleInfo moduleInfo)
Then you get the standard output.
The exception message was: The composition remains unchanged. The changes were rejected because of the following error(s): The composition produced multiple composition errors, with 57 root causes. The root causes are provided below. Review the CompositionException.Errors property for more detailed information.
1) Change in exports prevented by non-recomposable import 'EyeCue.Common.AboutEyeCueView.ViewModel (ContractName="EyeCue.Common.AboutEyeCueVM")' on part 'EyeCue.Common.AboutEyeCueView'.
WHat's puzzling is why none of the other 6 modules caused this problem but now all of a sudden, this new module without anything going on in it is causing a recomposition of the catalogue. It makes no sense.
Plus I have ctor's that import in some cases and that's they what I had to do to get things to work, so this is not as simple as going to setting the Allow Recomposition attribut.
I've downloaded the VisualMFX but this line of code throws an Object Not initialized exception.
this.compositionInfo = new CompositionInfo(_aggregateCatalog, _container);
Both _aggregateCatalog & _container are not null when this happens.
In summary, why would a 7th module all of a sudden start causing recomposition? Especially when the module isn't even defining any exports or imports at this time? That leads to how do we stop it to address this problem?
The issue turned out to be a reference to an assembly which had Copy Local set to true.
Making sure all references which are also set in the main application assembly were set to Copy Local = false seems to resolved the problem.
Building a Silverlight 5 app that runs in the browser but getting some nagging errors that are showing up in JavaScript, they aren't being caught by Visual Studio for some reason when the debugger is attached. I've done the simple stuff (create VS SL 5 project w/ a web project). When I'm debugging, the errors are showing up in the browser via JS... not in Visual Studio.
I can set breakpoints and walk through them, but when an unhandled exception happens, SL is just bubbling it up through the page (as expected), but VS isn't catching it.
I've verified that VS is attached to the IE process and the Type=Silverlight. Right now the bug I'm fighting with is the nagging 4004 error code (category=managedruntimeerror) with the message of "system.argumentexception: value does not fall within the expected range" but I can't find where that is happening w/o a stack more detail. All I get is the "Visual Studio JIT debugger" that looks very much like this http://www.scottleckie.com/2010/04/code-4004-unhandled-error-in-silverlight-application/ but his solution isn't working for me...
Look in your App.xaml.cs and you will find a handler called Application_UnhandledException.
There should be some code similar to this:
Deployment.Current.Dispatcher.BeginInvoke(delegate
{
ReportErrorToDOM(e);
});
Replace it with your custom error handling method. The ReporErrorToDOM is what triggers the javascript error in your browser.
If there isn't one you need to set one up:
public App()
{
this.UnhandledException += this.Application_UnhandledException;
...
}
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
// Handle exception here
...
// Don't forget this !
e.Handled = true;
}
I've had a few unexplained crashes happening on both the emulator and the phone itself. Basically when my app crashes I get no dialog box whatsoever and the phone returns to the home screen.
I have the following code to display a MessageBox but this is somehow being bypassed...
// Code to execute if a navigation fails
private void RootFrame_NavigationFailed(object sender, NavigationFailedEventArgs e)
{
MessageBox.Show(e.Exception.ToString());
}
// Code to execute on Unhandled Exceptions
private void Application_UnhandledException(object sender, ApplicationUnhandledExceptionEventArgs e)
{
MessageBox.Show(e.ExceptionObject.ToString());
}
The thought occurred to me that it might be related to memory, since my app deals with a lot of images. But I figure that would still be caught by my unhandled exception code above. Any ideas on how I should track this down would be appreciated.
Keep an eye on your memory usage. An OutOfMemoryException crashes your app without calling the Application_UnhandledException handler.
You can check the current memory usage with some built in methods. I blogged about this a while ago http://kodierer.blogspot.com/2010/09/windows-phone-memory-constraints.html
Here's the basic code you should add:
var timer = new DispatcherTimer {Interval = TimeSpan.FromSeconds(2)};
timer.Tick += (s, e) =>
{
var memuse = (long)DeviceExtendedProperties.GetValue("ApplicationPeakMemoryUsage");
var maxmem = (long)DeviceExtendedProperties.GetValue("DeviceTotalMemory");
memuse /= 1024 * 1024;
maxmem /= 1024 * 1024;
MyTextBlock.Text = String.Format("Mem usage: {0} / {1} MB", memuse, maxmem);
};
timer.Start();
A few things which have happened to me:
If you're doing things on other threads, then IIRC exceptions on those threads will cause the app to just terminate. You may want to wrap the new thread code in an exception handler which propagates the exception to the UI thread
If your app throws an exception before the first page is loaded, that can cause the app to just die without the appropriate handler being called
If you've got a StackOverflowException, that can't be caught and will just make the app bomb
You may want to add some debug-build-only persistent logging (loaded and displayed within the app itself) to make it easier to work out how far the previous run of the application had got before crashing.
My app crashed in exactly the same way.
I tracked it down to throwing an OutOfMemoryException inside a DispatcherTimer tick handler, though the problem probably occurs elsewhere as well.
However, it is not the case that an OutOfMemoryException always takes down your program. It does not. I tried it in various other handlers, and it was correctly caught.
I've posted a blog entry about lost exceptions here
Could your app be being watchdoged for being unresponsive for too long? Perhaps due to the load time of lots of images and this code being executed on the UI thread.
Is this a bug in Winforms? (tested on both VS2008 and VS2010)
private void Form1_Load(object sender, EventArgs e)
{
throw new Exception("Hey");
}
I don't receive any error in that code, awhile ago, I'm trying to formulate a solution for this question Parse a number from a string with non-digits in between
And I do this code in Form1_Load:
private void Form1_Load(object sender, EventArgs e)
{
MessageBox.Show("X");
string s = "12ACD";
string t = s.ToCharArray().TakeWhile(c => char.IsDigit(c)).ToArray().ToString();
MessageBox.Show("Y");
int n = int.Parse(t);
MessageBox.Show(n.ToString());
}
I wonder why it didn't show the number. Then on moving the code to button1_Click...
private void button1_Click(object sender, EventArgs e)
{
MessageBox.Show("X");
string s = "12ACD";
string t = s.ToCharArray().TakeWhile(c => char.IsDigit(c)).ToArray().ToString();
MessageBox.Show("Y");
int n = int.Parse(t);
MessageBox.Show(n.ToString());
}
...then I noticed that there's an error: Input string was not in a correct format.
Why Form1_Load didn't catch any exception, why it silently fail? The code just exit out of form1_load at string t = s.ToCharArray().TakeWhile...
Rewrite, I've since figured out where it comes from. Windows misbehaves when an exception is raised in a 32-bit process when it runs on a 64-bit version of Windows 7. It swallows any exception raised by code that runs in response to a Windows message that's triggered by the 64-bit windows manager. Like WM_SHOWWINDOW, the message that causes the Load event to get raised.
The debugger plays a role because when it is active, normal exception trapping in a Winforms app is turned off to allow the debugger to stop on an exception. That doesn't happen in this scenario because Windows 7 swallows the exception first, preventing the debugger from seeing it.
I've written about this problem more extensively in this answer, along with possible workarounds.
See this: The case of the disappearing OnLoad exception. It's by-design (though by-extremely-stupid-design, IMO). Your exception is hitting a kernel-mode boundary during the unwinding of the stack. If you can, switch to some other event, or don't let exceptions escape; this doesn't help if you're expecting your debugger to automatically break on an un-handled exception in OnLoad.
If you care, I wrote a bit more in this answer.
The WinForms framework classes won't automatically catch any exceptions for you. That isn't a bug, it's by design - what would they do with the exception?
You have to have your own try/catch block in any event or alternatively handle the Application.ThreadException event. That event can be helpful for some generic handling code like logging the exception or displaying an error dialog, but obviously it can't do anything specific to any individual event or exception type.