Unhandled exception in Windows Forms app

Question

I have a Windows Forms application. It loads assemblies with the extension .Plugin.dll with Assembly.LoadFile. One of these "plugins" calls into another assembly dll. That dll eventually throws a ValidationException exception. The method that throws the exception is in a class that inherits from IDataErrorInfo. This class is a class that is contained in a Linq to SQL class (.dbml). In the "plugin" I call DataContext.SubmitChanges. This is wrapped in a try/catch block. This causes my business logic to validate the data before submitting to the database in the OnValidate override. The result that I see is that after the ValidationExeption is thrown, the debugger stops at the bottom of the OnValidate method indicating that an unhandled exception has occured. If I continue to run the app my catch block is executed. That is what I wanted in the first place, but why am i getting an unhandled exception when it truly is handled?

Answer 1

I am 99% sure your "real" exception causing this is indeed unhandled -this is what the Debugger tells you at first place, and he is generally right.

When you continue to run the App in VS after that, it is not actually what would happen when you will execute your exe out of the debugger. In fact, the debugger notifies you first of the unhandled exception, and then continues some pending logic if any (that's why you see you ValidationException error). But the unhandled exception is still there. I don't exactly know the details and causes of this behavior, but I noticed this many times.

You have to catch the precise error at the precise place where the unhandledexception is thrown after you identify it. Maybe posting your code sample would help.

Answer 2

Firstly, is the plugin in the same AppDomain?

Secondly, it sounds to be like you have your debugger to "Break when exception is thrown" rather than "Break when exception is user-unhandled".

In VS.NET, go to Debug --> Exceptions...

Expand the "Common Language Runtime Exceptions" node and see if any are ticked.