Thanks for reply,

All classes a, b, c and d are actually defined within one dll (one module). I forgot to mention it.
I can do this following thing:

d* pD = mew d();

and then
ar & boost::serialization::make_nvp("item", pD);

but
c* pD = new D();
ar & boost::serialization::make_nvp("item", pD);

does not work at all! It throws this strange type of exceptions which I cannot handle at all.
Another problem is that if I do the first version the member m_key variable of true_type in the call

const boost::serialization::extended_type_info * true_type =
i.get_derived_extended_type_info(t);

is a null pointer which is not right. Do you have any idea what could be wrong?

Thanks a lot for help

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