C# Backgroundworker Error Handling
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in BackgroundWorker up vote 55 down vote favorite 15 I have a small WinForms app that utilizes a BackgroundWorker object to perform a long-running operation. The background operation throws occasional exceptions, typically when somebody has a file open that is being recreated. Regardless of whether the code is run from the IDE or not .NET pops up an error dialog informing the user that c# exception bubble up an Unhandled exception has occurred. Compiling the code using the Release configuration doesn't change this either. According to MSDN: If the operation raises an exception that your code does not handle, the BackgroundWorker catches the exception and passes it into the RunWorkerCompleted event handler, where it is exposed as the Error property of System.ComponentModel..::.RunWorkerCompletedEventArgs. If you are running under the Visual Studio debugger, the debugger will break at the point in the DoWork event handler where the unhandled exception was raised. I expect these exceptions to be thrown on occasion and would like to handle them in the RunWorkerCompleted event rather than in DoWork. My code works properly and the error is handled correctly within the RunWorkerCompleted event but I can't for the life of me figure out how to stop the .NET error dialog complaining about the "Unhandled exception" from occurring. Isn't the BackgroundWorker supposed to catch that error automagically? Isn't that what the MSDN documentation states? What do I need to do to inform .NET that this error is being handled while still allowing the exception to propage into the Error property of RunWorkerCompletedEventArgs? c# exception backgroundworker unhandled-exception share|i
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Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. http://stackoverflow.com/questions/1044460/unhandled-exceptions-in-backgroundworker Join them; it only takes a minute: Sign up error handling with BackgroundWorker up vote 4 down vote favorite I know, that you can handle BackgroundWorker errors in RunWorkerCompleted handler, like in next code var worker = new BackgroundWorker(); worker.DoWork += (sender, e) => { throw new InvalidOperationException("oh shiznit!"); }; worker.RunWorkerCompleted += (sender, e) => { if(e.Error != null) http://stackoverflow.com/questions/3966557/error-handling-with-backgroundworker { MessageBox.Show("There was an error! " + e.Error.ToString()); } }; worker.RunWorkerAsync(); But my problem is that i still receive a message : error was unhadled in user code on line throw new InvalidOperationException("oh shiznit!"); How can i resolve this problem ? c# winforms share|improve this question asked Oct 19 '10 at 8:36 mike 2112 Do you test this in a WinFormss app? Or Console? –Henk Holterman Oct 19 '10 at 9:21 add a comment| 2 Answers 2 active oldest votes up vote 7 down vote You receive it because you have a debugger attached. Try to start the application without a debugger: no exception is fired and when the worker completes the operation show you the MessageBox. share|improve this answer answered Oct 19 '10 at 8:41 as-cii 9,03013037 yes, this is correct –mike Oct 19 '10 at 8:43 4 mark it as the answer then! –Tim Oct 20 '10 at 14:32 add a comment| up vote 1 down vote I cannot reproduce the error. The following works fine: public parti
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Question Need help? Post your question and get tips & solutions from a community of 418,461 IT Pros & Developers. It's quick & easy. throw/handle exceptions while using backgroundworker P: n/a chris hello, I can't seem to make this work: VS2005 I have a simple program that uses a backgroundworker control to execute a long process (webservice call) if that webservice call fails, i want to raise an exception and display a messagebox. however no matter where i put the Try block to trap the error, it does not work. the only example i could find on it is here: http://msdn2.microsoft.com/en-us/library/4852et58.aspx in which case they do this: Private Sub backgroundWorker1_RunWorkerCompleted( _ ByVal sender As Object, ByVal e As RunWorkerCompletedEventArgs) _ Handles backgroundWorker1.RunWorkerCompleted ' First, handle the case where an exception was thrown. If Not (e.Error Is Nothing) Then MessageBox.Show(e.Error.Message) ElseIf e.Cancelled Then however, i can't figure out how to set the e.Error in the RunWorkerCompletedEventArgs. that same example from the msdn site has the following lines of code in the procedure that's being called by the backgroundworker: ' The parameter n must be >= 0 and <= 91. ' Fib(n), with n > 91, overflows a long. If n < 0 OrElse n > 91 Then Throw New ArgumentException( _ "value must be >= 0 and <= 91", "n") End If but this example does not work. the actual numericUpDown control in the form is set to not allow any values outside those parameters, so the exception condition ( If n < 0 OrElse n > 91 ) is never true. if you actually passs something outside of those values to the procedure, you get the following error when the "Throw New ArgumentException..." line is executed: ArgumentException was unhandled by user code. this is the same problem that i have. to repeat this, copy the example code from http://msdn2.microsoft.com/en-us/library/4852et58.aspx and change the Maximum property on the numericUpDown1 control to something greater than 91. run the program, enter the value 92 in the numericUpDown1 control, and click Start. the Throw New ArgumentException line generates an error. does anybody know how to get the e.Error in the RunWorkerCompletedEventArgs to work? thanks, chris. Jan 25 '06 #1 Post Reply Share this Question 3 Replies P: n/a Jay B. Harlow [MVP - Outlook] Chris, | does anybody know how to