It is mandatory to use this function inside your finalizer to guard the finalizer thread against exceptions. Determines whether the specified exception is fatal and should be propagated to the next layer regardless of your current exception policy. An exception is considered fatal is it is one of the following types: NullReferenceException, StackOverflowException, OutOfMemoryException, ThreadAbortException, ExecutionEngineException, IndexOutOfRangeException or AccessViolationException