I did not see boost serialisation in the list of lib that had changed. So its surprising that it now broken ? It appears simply including it cause problems #include cause gcc.compile.c++ bin/gcc-4.5/debug/test/TestStr.o In file included from /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr.hpp:28:0, from test/TestStr.cpp:27: /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp: In static member function ‘static const boost::serialization::extended_type_info* boost::serialization::shared_ptr_helper<SPT>::non_polymorphic::get_object_type(U&)’: /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:107:22: error: ‘singleton’ is not a member of ‘boost::serialization’ /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:110:13: error: expected ‘(’ before ‘>’ token /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:110:14: error: ‘::get_const_instance’ has not been declared /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp: In static member function ‘static const boost::serialization::extended_type_info* boost::serialization::shared_ptr_helper<SPT>::polymorphic::get_object_type(U&)’: /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:117:20: error: ‘singleton’ is not a member of ‘boost::serialization’ /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:120:13: error: expected ‘(’ before ‘>’ token /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:120:14: error: ‘::get_const_instance’ has not been declared /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp: In member function ‘void boost::serialization::shared_ptr_helper<SPT>::reset(SPT<T>&, T*)’: /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:152:30: error: invalid use of incomplete type ‘const struct boost::serialization::extended_type_info’ /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:42:7: error: forward declaration of ‘const struct boost::serialization::extended_type_info’ /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:167:30: error: invalid use of incomplete type ‘const struct boost::serialization::extended_type_info’ /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:42:7: error: forward declaration of ‘const struct boost::serialization::extended_type_info’ /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:168:30: error: invalid use of incomplete type ‘const struct boost::serialization::extended_type_info’ /var/tmp/ma0/boost/boost_1_56_0/boost/serialization/shared_ptr_helper.hpp:42:7: error: forward declaration of ‘const struct boost::serialization::extended_type_info’ "g++" -ftemplate-depth-128 -fPIC -O0 -fno-inline -Wall -g -fPIC -DDEBUG -I"../ACore/src" -I"/var/tmp/ma0/boost/boost_1_56_0" -c -o "bin/gcc-4.5/debug/test/TestStr.o" "test/TestStr.cpp" Are there any workarounds ? Ta, Avi