Hi, thanks to Roberts help I managed to get the polymorphic archives issue, discussed earlier at http://article.gmane.org/gmane.comp.lib.boost.devel/196984), resolved. However there remains a runtime issue I can't resolve: Based on demo_polymorphic.cpp I've re-created minimal test example, which I think is correct, that fails with the runtime assertion it != m_map.end(), file libs\serialization\src\basic_serializer_map.cpp, line 72 on load. The demo consists of 5 files that create the following scenario: class B inherits from polymorphic base class A. An object of B is allocated on the heap and serialized through a base pointer A using a polymorphic xml archive. Saving runs without problems. Next, B is loaded from the stream through a base pointer to A. This fails with the mentioned assertion. What makes me wonder is that changing the from polymorphic_xml_iarchive to xml_iarchive and from polymorphic_xml_oarchive to xml_oarchive will not produce the named assertion. As mentioned in my previous post, I tested this with boost 1.40.0 and msvc 9.0. I would be really, really, grateful if you could give the demo a try. I've prepared everything so that it is just a matter of copying the files to libs/serialization/example and adding [ demo_bsl_run demo_polymorphic_cheind : cheind_a cheind_b ] The files can be found attached to my lost post at http://article.gmane.org/gmane.comp.lib.boost.devel/197061 Best regards, Christoph