I am working with the boost 1.40.0 serialization library and I am having trouble with class registration for polymorphic types. The code I have has worked fine with VS2005 and VS2008 for a long time; however, in linux with gcc (4.4.1-4ubuntu9), I am having issues. I am using the non-intrusive serialization method on a class that resides in a shared object file. I have simplified this down to where the serialization of the object is performed in an executable linking in the shared object file. In Windows I am registering the classes with boost using BOOST_CLASS_EXPORT_GUID. However, in linux, if I register the classes using this macro, the code compiles but does not link and gives an error similar to below for : testConfig.o: In function `boost::archive::detail::iserializer<boost::archive::text_iarchive, MyNamespace::MyDerivedClass>::load_object_data(boost::archive::detail::basic_iarchive&, void*, unsigned int) const': testConfig.cpp:(.text._ZNK5boost7archive6detail11iserializerINS0_13text_iarchiveEN7MoreOfMyClassRelatredDataEE16load_object_dataERNS1_14basic_iarchiveEPvj[boost::archive::detail::iserializer<boost::archive::text_iarchive, MyNamespace::MyDerivedClass>::load_object_data(boost::archive::detail::basic_iarchive&, void*, unsigned int) const]+0x96): undefined reference to `MyNamespace::MyBaseClass& boost::serialization::base_object<MyNamespace::MyBaseClass, MyNamespace::MyDerivedClass>(MyNamespace::MyDerivedClass const&)' The same error also occurs with save_object_data. If I don't register, my test fails with the unregistered class exception. I have tried placing the macros in both a header and a source file and I still get the linker errors following advice from here: http://www.boost.org/doc/libs/1_40_0/libs/serialization/doc/special.html#exp.... I also tried explicitly instantiating the base_object methods, but get an error indicating no matching definition exists, so I am assuming this is related to the issue - I'm just not sure how else to define the function. I am familiar with basic templating, but the serialization library source is beyond me. Any help would be greatly appreciated..... Thanks - John -- View this message in context: http://old.nabble.com/undefined-reference-to-base_object-tp28417529p28417529... Sent from the Boost - Users mailing list archive at Nabble.com.