Hi, I've posted this with no luck to the boost-users mailing list: the attached example [1] generates a couple of linker [2] errors on msvc 9.0 / boost 1.40.0 all related to missing archive_serializer_map symbols. when switching from polymorphic archives to corresponding non-polymorphic archives the attached example runs fine. It seems that the usage of BOOST_CLASS_EXPORT in conjunction with polymorphic archives triggers the linker error. I tried to add explicit template instantiations, such as [3], for the missing types to boost archive, recompiled boost and was able to get rid of the linker error. The problem then, however, is that the example fails at runtime with an assertion that a type-lookup did not succeed. So I guess adding the explicit template instantiations was not the correct approach. Is this a bug? Can anyone confirm this issue? Best regards, Christoph