Hi zopistas... Hmmm seems that the main question is in the title but here's the background... I made a business logic object that must be customized with options and TTW Python scripts. Some of the methods used from Python scripts may raise specific custom exception but I didn't get the way making those exceptions available to Python scripts. As a workaround, I use builtin exceptions like IOError and others in a bad way. What I would like to do... from Products.MyProduct.MyExceptions import InvalidDateRangeError ... try: # do some stuff except InvalidDateRangeError, e: # do other stuff Many thanks in advance for your hint. -- Gilles