Unmanaged Exceptions

Question

I have a method that calls an unmanaged library from a background thread. I put a try catch block around the unmanaged call but it is never caught. The just in time debugger catches it instead. What am I doing wrong?

    public bool TurnOn()
    {
        var connectionSucceeded = false;
        try
        {
            connectionSucceeded = turnOn(); //Unmanaged call
        }
        catch
        {
            connectionSucceeded = false; //Never reaches this block                
        }

        return connectionSucceeded;
    }

you use .net 4.0? In .net 4.0 this problem may be, when in 3.5 not. — Sonorx, Mar 19 '11 at 19:09

score 1 · Answer 1 · answered Mar 19 '11 at 19:02

1

Is the debugger setup to handle unmanaged exceptions when they are thrown?

Check the setting in Debug>Exceptions

Also, is the unmanaged exception definitely thrown on the thread directly being called - and not in some async operation on a different thread?

answered Mar 19 '11 at 19:02

Stuart

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Either way it should either show up in the catch block or the UnhandledException event. It does not do either. – Robert Mar 19 '11 at 19:29
If it's thrown on a new thread - one created by the native code - then I don't think it will show up in your handler. – Stuart Mar 19 '11 at 19:30
How would I catch something like that? – Robert Mar 19 '11 at 19:38
AFAIK, I'm not sure you can - if it's a native exception on a thread without any native try/catch handling, then I think that's game over. But first of all, is there any way you can check that this is actually the problem - e.g. what does the native stack trace show you? What is the native "turnon"? Is it something you have the pdb/dbg symbols or the source code for? – Stuart Mar 19 '11 at 19:56
I do not have any pdb/dbg symbols or any access to the source. – Robert Mar 19 '11 at 20:06
does the turnon method throw an exception if called from native code? - e.g. from a native C++ app? – Stuart Mar 19 '11 at 20:14

score 1 · Answer 2 · edited May 23 '17 at 12:04

1

I fully agree with Stuart answer.. In this case you could try catch exception on application level:

AppDomain.CurrentDomain.UnhandledException += UnhandledExceptionEventRaised;

Plz see also this answer: AppDomain.CurrentDomain.UnhandledException not firing without debugging

edited May 23 '17 at 12:04

Community

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answered Mar 19 '11 at 19:09

mastak

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Sorry let me be more clear. That event does fire, just not in the case of unmanaged exceptions. – Robert Mar 21 '11 at 00:27
Plz look to referenced answer and try it. – mastak Mar 21 '11 at 13:09
1

The referenced answer uses winforms methods as part of the solution, I'm using wpf – Robert Mar 21 '11 at 16:14

Unmanaged Exceptions

2 Answers2