Sometimes its impossible to load requested resource for some reason. Unavailability of resource often does not lead to crash of conversiov and result document can be created anywaybut maybe in a bit worse quality without Images etc.. If exception occured during loading just catch it and put in this parameter - sometimes that information is usefull for converter for Rendering of result....bit worse quality, without images etc.). If exception occured...usefull for converter for rendering of result. public Exception...