Hi, I have a problem with the deserialization of objects defined in multiple dlls. I define the following classes in a first dll: polymorphic_base (pure virtual) and polymorphic_derived1 (derived from polymorphic_base). In a second dll, I define the class polymorphic_derived2 (derived from polymorphic_derived1). In an executable, I serialize an object of type polymorphic_derived2 followed and two objects of type polymorphic_derived1 in the order defined in this function: void save_exported (const char *testfile) { std::ofstream os(testfile); xml_oarchive oa(os); polymorphic_base * pb_ptr_1 = new polymorphic_derived1; oa << BOOST_SERIALIZATION_NVP(pb_ptr_1); polymorphic_base * pb_ptr_2 = new polymorphic_derived2; oa << BOOST_SERIALIZATION_NVP(pb_ptr_2); polymorphic_base * pb_ptr_3 = new polymorphic_derived1; oa << BOOST_SERIALIZATION_NVP(pb_ptr_3); } The serialization works, but when, I try to deserialyze with this function: void load_exported(const char *testfile) { std::ifstream is(testfile); xml_iarchive ia(is); polymorphic_base * pb_ptr_1 = NULL; ia >> BOOST_SERIALIZATION_NVP(pb_ptr_1); polymorphic_base * pb_ptr_2 = NULL; ia >> BOOST_SERIALIZATION_NVP(pb_ptr_2); polymorphic_base * pb_ptr_3 = NULL; ia >> BOOST_SERIALIZATION_NVP(pb_ptr_3); // <= exception } an exception is thrown on the deserialization of the second object of type polymorphic_derived1 but it works for the first one. in the file basic_archive.cpp, line 466 : "pending_bis = & bpis_ptr->get_basic_serializer();" bpis_ptr is null. It seems that the deserialization of the object of type polymorphic_derived2 (derived from polymorphic_derived1) has broken the part of table cobject_id_vector concerning polymorphic_derived1. If polymorphic_derived2 is defined in the first dll, there is no problem. Is it possible to make it works with 2 dll? Regards, Yohan