#917 – Corrupted State Exceptions Are Not Normally Caught

Starting with .NET 4.0, there are a class of exceptions that will not be caught within a general catch block that catches all exceptions deriving from System.Exception.  By default, a corrupted state exception will not be caught as a System.Exception.  A corrupted state exception is a type of exception, like an access violation, that likely results in the internal state of the process being corrupt.

In the example below, we artificially generate an access violation.  Note that the exception that is raised is not caught, but treated as an unhandled exception.  (Our catch block never executes).

        static void Main(string[] args)
        {
            try
            {
                Console.WriteLine("Before call to CausesAccessViolation()");
                CausesAccessViolation();
                Console.WriteLine("Before call to CausesAccessViolation()");
            }
            catch (Exception exc)
            {
                Console.WriteLine(string.Format("Hey, I caught an Exception: {0}", exc.ToString()));
            }

            Console.ReadLine();
        }

        static void CausesAccessViolation()
        {
            IntPtr ptr = new IntPtr(123);
            Marshal.StructureToPtr(123, ptr, true);
        }

917-001