Try/Catch Block Fails to Catch Exception

Question

My program is generating a System.ComponentModel.Win32Exception within a try/catch block and the exception is not being caught. The code is very simple:

try
{
    lAFE.MinimumSize = sz1;  // lAFE=Label, sz1 = Size
}
catch (Exception ex)
{
    MessageBox.Show("afe: " + ex.Message);
}

The program runs through this code block hundreds of times without a problem then suddenly it generates this exception and it is not caught.

What can cause an exception like this not to be caught.

This application uses a lot of memory and the exception always occurs when the memory usage reaches about 305KB.

Any advice would be greatly appreciated.

Answer 1

Because Win32 exceptions do not derive from the .NET Exception class. Try :

try 
{
} 
catch (Exception ex) 
{
    // .NET exception
} 
catch 
{
    // native exception
}

You can read this article:

A catch block that handles Exception catches all Common Language Specification (CLS) compliant exceptions. However, it does not catch non-CLS compliant exceptions. Non-CLS compliant exceptions can be thrown from native code or from managed code that was generated by the Microsoft intermediate language (MSIL) Assembler. Notice that the C# and Visual Basic compilers do not allow non-CLS compliant exceptions to be thrown and Visual Basic does not catch non-CLS compliant exceptions. If the intent of the catch block is to handle all exceptions, use the following general catch block syntax.

C#: catch {}