6
That is unfortuneate. It is going to become increasingly more and more difficult for you to get support as time goes on.
The really sad part in all this, is that because you have apparently modified your core. There is no reall way for us to guess at the problem.
Essentially you dug yourself into a whole. My suggestion would be to set up a fresh installation of 2.0.15 and move everything over piece by piece.
BOL