Jeremy Jeremy -4 years ago 136
C# Question

How to handle AccessViolationException

I am using a COM object (MODI) from within my .net application. The method I am calling throws a System.AccessViolationException, which is intercepted by Visual Studio. The odd thing is that I have wrapped my call in a try catch, which has handlers for AccessViolationException, COMException and everything else, but when Visual Studio (2010) intercepts the AccessViolationException, the debugger breaks on the method call (doc.OCR), and if I step through, it continues to the next line instead of entering the catch block. Additionally, if I run this outside of the visual studio my application crashes. How can I handle this exception that is thrown within the COM object?

MODI.Document doc = new MODI.Document();
try
{
doc.Create(sFileName);
try
{
doc.OCR(MODI.MiLANGUAGES.miLANG_ENGLISH, false, false);
sText = doc.Images[0].Layout.Text;
}
catch (System.AccessViolationException ex)
{
//MODI seems to get access violations for some reason, but is still able to return the OCR text.
sText = doc.Images[0].Layout.Text;
}
catch (System.Runtime.InteropServices.COMException ex)
{
//if no text exists, the engine throws an exception.
sText = "";
}
catch
{
sText = "";
}

if (sText != null)
{
sText = sText.Trim();
}
}
finally
{
doc.Close(false);

//Cleanup routine, this is how we are able to delete files used by MODI.
System.Runtime.InteropServices.Marshal.FinalReleaseComObject(doc);
doc = null;
GC.WaitForPendingFinalizers();
GC.Collect();
GC.WaitForPendingFinalizers();

}

Answer Source

In .NET 4.0, the runtime handles certain exceptions raised as Windows Structured Error Handling (SEH) errors as indicators of Corrupted State. These Corrupted State Exceptions (CSE) are not allowed to be caught by your standard managed code. I won't get into the why's or how's here. Read this article about CSE's in the .NET 4.0 Framework:

http://msdn.microsoft.com/en-us/magazine/dd419661.aspx#id0070035

But there is hope. There are a few ways to get around this:

  1. Recompile as a .NET 3.5 assembly and run it in .NET 4.0.

  2. Add a line to your application's config file under the configuration/runtime element: <legacyCorruptedStateExceptionsPolicy enabled="true|false"/>

  3. Decorate the methods you want to catch these exceptions in with the HandleProcessCorruptedStateExceptions attribute. See http://msdn.microsoft.com/en-us/magazine/dd419661.aspx#id0070035 for details.

For more reference: http://connect.microsoft.com/VisualStudio/feedback/details/557105/unable-to-catch-accessviolationexception

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