I have an app that used to work well, I did some modifications and such. Now, only about 1/2 the time it runs. I installed the app to a laptop and it doesn't run at all.
There are no errors, warnings, or ui shown by the task bar shows the app momentarily.
Even when I run inside visual studio and put a break point on InitalizeComponent(), I can't seem to locate anything causing the problem.
My code essentially looks like this:
Application.Current.DispatcherUnhandledException += Current_DispatcherUnhandledException;
this.Dispatcher.UnhandledException += Dispatcher_UnhandledException;
try
{
InitializeComponent();
}
catch (Exception ex)
{
MessageBox.Show(ex.Message);
}
log("Initalizing....");
This is wpf 4 in vs2015. Any ideas how to get some type of error message before it exits and figure out what is causing the problem? The app works fine once it actually runs. The event viewer on the laptop shows some messages, something about faulting in KernalBase.... nothing useful.
I'm not sure if InitalizeComponent() is the issue, but when I put a BP on it and step through the code, it always exits at that point.
As #Breeze mentioned, you need to strengthen the exceptions, like that:
Go to Debug -> Exceptions... OR Ctrl+Alt+E and you'll see this window:
Mark this two:
Common Language Runtime Exceptions and
Manage Debbugging Assistants.
REMEMBER after finish using them unmark them because it also throws exceptions you don't need to deal with a lot of times.
Related
Having some trouble with try/catch in UiPath:
Got two different projects with their own workflows, with try catch implementations exactly the same in both.
However, one of the try/catch is working absolutely fine, whereas the other one is giving troubles with the following error when I Throw an exception, and then the steps defined in the catch block doesn't even trap it and execute.
Thoughts/Suggestions will be much appreciated - Thanks!
RemoteException wrapping System.Exception: <My user defined message>
at System.Activities.Statements.Throw.Execute(CodeActivityContext context)
at System.Activities.CodeActivity.InternalExecute(ActivityInstance instance, ActivityExecutor executor, BookmarkManager bookmarkManager)
at System.Activities.ActivityInstance.Execute(ActivityExecutor executor, BookmarkManager bookmarkManager)
at System.Activities.Runtime.ActivityExecutor.ExecuteActivityWorkItem.ExecuteBody(ActivityExecutor executor, BookmarkManager bookmarkManager, Location resultLocation)
If you have been using the Try Catch with the general Exception, it should be working in the same way in any project.
I believe you was a bit confused by the running mode.
So I assume in one project you fired the project in the debug mode. This stops on the exception when it occurs. If happening you need to hit the continue button.
But if you run the project with the Run button, it will ignore the exception handling as breakpoint and will continue now without any break.
So make sure in a live test you always run it with the run button and not with the usual debug button.
Within a Codename1 app, I'm getting a CrashReport: java.lang.NullPointException: Attempt to invoke virtual method 'void android.graphics.Point.setAntiAlias(boolean)' on a null object reference. This seems to occur after I invoke a "show()" on the main form of my application.
Note that the code runs fine in the simulator, but consistently gets this error prior to doing the "show()" on Android.
Interestingly, if I put a Dialog like this:
Dialog.show("Wait a sec", "Showing interrupt point", "OK", null);
before the .show(), and then click "OK", then everything runs well with no exceptions at all.
But a sleep(5000) instead of the Dialog does not help - still get the exception. So it at least seems like its not a race condition.
I have try-catches wrapped around all of the potentially offending code, and have NOT been able to isolate this. It always gets caught by the CrashReport, and only when running on the Android device.
Any ideas?
The symptoms to this one are pretty strange (i.e. workaround with a Dialog), and it would be interesting to have an explanation. However, since deprecated cn1 (Map) code has seemingly been implicated, I'm going to let this one go and replace this code with the latest Google native maps code. If it recurs, I will post another question then.
Since a few days back the WPF editor no longer works. Whenever I click somewhere in any editor it becomes disabled with this message:
'NullReferenceException was thrown on "DataTemplate": ... (etc.)'
I have spent a few hours trying to locate the problem without success so if anyone could give a hint on where to look I would greatly appreciate it.
I have tried to debug with CLR exceptions enabled when thrown (VS2010->Debug->Exceptions...->Common Language Exceptions (Thrown) 'Checked') but I get no exceptions from it.
Apparently there's a problem some DataTemplate somewhere that's only showing in design time but I just can't figure out how to locate it.
Cheers
I finally traced the problem to a small markup extension I wrote. Having removed it the DataTemplaring system stopped behaving badly.
I run into the following issue semi-regularly: I make changes to XAML or some resources used by it and when I go to load up the Silverlight project in debug mode it only gets as far as the spinning Silverlight-loading animation.
I've tried attaching the VS08 debugger to the process but it doesn't do anything at this point (works fine once I'm in the Silverlight but not before.)
From previous experience I've noticed this happens when there're problems with the XAML or the resources in it but my only solution so far has been to dissect the code line-by-line until I spot the problem.
Is there an easy way to debug/diagnose these situations?
UPDATE
I found this question with some help, but it still doesn't provide a good way to debug these types of issues.
This has been a real pain to debug but I finally found the problem hidden deep in the constructor to one of our custom controls (which was looking for a resource that wasn't there.) The real problem isn't fixing the issue but finding it.
I found that IE responds to exceptions in passed from Silverlight to the DOM but you don't get that same sort of feedback in the Chrome browser (which I use.) A solution that actually helps a great deal (even moreso than the IE tip) is to modify the ReportErrorToDOM() method in App.xaml.cs to the following:
private void ReportErrorToDOM(ApplicationUnhandledExceptionEventArgs e)
{
string errorMsg = String.Empty;
try
{
errorMsg = e.ExceptionObject.Message + e.ExceptionObject.StackTrace;
errorMsg = errorMsg.Replace('"', '\'').Replace("\r\n", #"\n");
System.Windows.Browser.HtmlPage.Window.Eval("throw new Error(\"Unhandled Error in Silverlight Application " + errorMsg + "\");");
}
catch (Exception)
{
#if DEBUG
MessageBox.Show(errorMsg);
#endif
}
}
This gives you the position in the XAML where the issue is starting. It's not an ideal debugger, but it does help.
This is not the ultimate answer but can often help
In Visual Studio :
Click Debug > Exceptions
Click 'Find' and search for XAML
Click the 'Thrown' button next to System.Windows.Markup.XamlParseException
Start your project in debug mode. Any Xaml exceptions will be shown immediately. Check the inner exception sometimes for further information.
I wasted soooo much time before I finally figured this one out!
This may not apply, but one frequent source of XAML errors is due to uncaught exceptions within converters that you're using as resources. People often forget to use a try-catch block in their converters, and when something blows up in there you end up having to dissect your code line by line.
And, take this with a grain of salt, but depending upon the situation, you may be able to copy-and-paste some of your XAML into a WPF project and get better error messages. I've never relied on this tactic myself, but I recently heard about it from an experienced WPF/SL developer who's far smarter than me, so it might be worth a shot. :-)
Per microsoft: The end user at this time cannot debug the XAML Parser, only MS can do this. The new version of Silverlight 4 XAML Parser has been completely re-written using managed code and hopfully they will give us a better way to debug it. I know this as I just had an issue and opened a support case and was informed this by a Silverlight Dev.
The clkosest I could ever come to seeing what was going on with the parser was using Silverlight Spy:
http://firstfloorsoftware.com/silverlightspy/download-silverlight-spy/
Great tool.
when I use XamlReader.Load() with an invalid XAML string, the resulting XAMLParseException is not caught although beeing in a try-catch-block:
try
{
UIElement xamlCode = XamlReader.Load(XamlText) as UIElement;
}
catch (Exception ex)
{
ErrorText = ex.Message;
}
The code is called from the Tick-Event of a DispatcherTimer, but also in Events like MouseLeftButtonDown the exception is not caught resulting in a break in the Line where I call .Load().
Does anyone know how to catch this Exception and resume normal programm activity?
Thanks, Andrej
It is completely unfathomable that this code would not catch the exception. How do you determine that the XAMLParseException is occuring here? Are you sure is not coming from some other Xaml Load in the project?
Is this always the case ? or onlys while debugging ?
I'm aware this is an extremely late answer and you might have found the solution to it, for as reference to people finding your question similar to theirse (like my case ), my answer might still be of use.
If its happening while debuggin, it might be because the exeption is configured to be thrown.
You can change this:
Customize the Debug menu, adding the "Exceptions" command to it.
In the Exceptions configuration, Drill down to System.Windows.Markup.XamlParseException, which is under Common Language Runtime Exceptions.
Remove the check from the "Throw" column.
There are various Silverlight operations that get "re-marshalled" onto separate threads for what are presumably various good and sufficient reasons. It looks kind of like this:
Dispatcher.BeginInvoke(() => LoadSomeXamlOrSomething());
Any exception thrown within LoadSomeXamlOrSomething() won't be caught by normal try/catch blocks. This happens even in SL 4 with things like loading images with invalid formats. It's annoying, and MS needs to come up with a better way to handle this, for instance, by letting you register an exception handler when you make the call.
Until MS figures this out, your options are:
Fix the underlying XAML error.
Catch the exception in App.Application_UnhandledException.