Hi, I used boost serialization to write my data in binary format as in below way - std::ofstream ofs(catalogFileName.c_str(),std::ios::binary); boost::archive::binary_oarchive oa(ofs); //write oa & m_myclass; // object of CMyClass type containing some data (say name) This worked correctly. Now I wanted to write into xml format. Did the below changes std::ofstream ofs(catalogFileName.c_str(),std::ios::binary); boost::archive::xml_oarchive oa(ofs); //write oa & m_myclass; But it is giving me below error - d:\tools\boost-1feb08\boost_1_34_1\boost\archive\basic_xml_oarchive.hpp( 83) : error C2027: use of undefined type 'boost::STATIC_ASSERTION_FAILURE<x>' Can you help me to identify the problem? FYI - I have made no changed CMyClass looks like as below. And I have made no changes in it (same one used for binary and xml) class CMyClass { public: Part(const std::wstring& Name); private: std::wstring m_name; friend class boost::serialization::access; template<class Archive> void serialize(Archive& ar, const unsigned int) { ar & m_name; } }; Thanks in advance. Regards, Mukund