C# 3.0 Cookbook, 3rd Edition

7.9. Breaking on a First-Chance Exception

Problem

You need to fix a problem with your code that is throwing an exception. Unfortunately, an exception handler is trapping the exception, and you are having a tough time pinpointing where and when the exception is being thrown.

Forcing the application to break on an exception before the application has a chance to handle it is very useful in situations in which you need to step through the code at the point where the exception is first being thrown. If this exception were thrown and not handled by your application, the debugger would intervene and break on the line of code that caused the unhandled exception. In this case, you can see the context in which the exception was thrown. However, if an exception handler is active when the exception is thrown, the exception handler will handle it and continue on, preventing you from being able to see the context at the point where the exception was thrown. This is the default behavior for all exceptions.

Solution

Select Debug → Exceptions or use the Ctrl-D key combination and then the E key within Visual Studio 2008 to display the Exceptions dialog box (see Figure 7-1). Select the exception from the tree that you want to modify and then click on the checkbox in the Thrown column in the list view. Click the OK button and then run your application. Any time the application throws a System.ArgumentOutOfRangeException, the debugger will break on that line of code before your application has a chance ...