I quote the Boost serialization docs: When serializing an object through a pointer to its base class and that base class is abstract (i.e. has at least one virtual function assigned a value of 0), A compile error will be emitted. This is addressable in one over several ways: * remove the =0 in the base classes so that the base class is no longer abstract. * implement is_abstract for your compiler. (code written according to the C++ standard is included with this library. But it is known to fail on several compilers. * use the macro BOOST_IS_ABSTRACT(my_class) to indicate that the class is an abstract base class. This will cause the compiler to avoid generating code that causes this error. I still do not understand part 2 of this advice, Robert. Could you explain? Jean-Noël Ps: as already mentioned, part 3 does not change anything for me, and I'd like to avoid the solution of part 1 since I do want the base class to be abstract.