Hello, My program crashes at launch (not even a exit(0) as the first line of main(int argc, char *argv[]) will stop it from crashing), due to the BSL. What I am trying to do is: I have a class, whose serialization is split (eg, save and load functions are provided, and they are different). Now this class had a parent class, so I used to call boost::serialization::base_object<MObject>() on the base class MObject. However I want to change the parent of my class to a different class. I also want to update my old archives, so I decided to leave the load function of my class untouched, while I would change the save function, to update the call to base_object to the new parent class (not MObject anymore). I thought it would work, since it would load the old archive using the same method, but save it using the new, so I would have ran only one time the program and the archive would be updated (then, of course, before running it again I would have to recompile it one more time with the correct changes to the load function). But it does not work as expected, since it seems the BSL does not like the fact that save and load functions calls to boost::serialization::base_object do not specify the same base class. It does not complain at compile time but crashes at run time before even entering main and certainly before loading any archive. The crash is due to a NULL pointer, I have tried to debug with gdb but the crash apparently occurs on the _libkernel32_a_iname () so I do not not know where it is (too low level for me). Robert, do you have an idea what is going on? I suspect a bug - however if it is "normal" behaviour (I think it should then throw an exception rather than crash), do you have an idea how could I update my archives? I need to change the parent of this class, but need to be able to read my old archives - and changing them "by hand" by looking into the XML archive code is tool hard. Thank you, regards Jean-Noël Rivasseau