How can I handle the exception which throws on an external dll?

Question

I have developed a project which uses an external dll as FTPServer, I have created the FTP Server on my project like this:

private ClsFTPServer _ClsFTPServer;

Answer 1

In case of using external unmanaged\unsafe code, .NET (above .net 4) by default cannot handle Memory Access Violation exceptions that happens inside of dll code. in order to catch these kind of exceptions, there is three things to do. I did them and it worked for me:

1. Add these Attributes to the method that exception occurred inside of it :
   (the method that calls the method of the unmanaged code.)

   [HandleProcessCorruptedStateExceptions]
   [SecurityCritical]
   

2. Add this tag to App.Config file below runtime tag :

3. Catch these kind of exception by using System.AccessViolationException exception type :

     try{
           //Method call that cause Memory Access violation Exeption
        }
   catch (System.AccessViolationException exception)
        {
           //Handle the exception here
         }
   

What i said is just the cure for these type of exception. for more information about this exception's ego and how this approach works, see System.AccessViolationException