I am getting these errors while building one of my projects where boost serialization headers are included 1>..\..\..\ThirdParty\Boost\boost/config/abi_prefix.hpp(19) : error C2220: warning treated as error - no 'object' file generated 1>..\..\..\ThirdParty\Boost\boost/config/abi_prefix.hpp(19) : warning C4103: 'x:\thirdparty\boost\boost\config\abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 1>..\..\..\ThirdParty\Boost\boost/serialization/extended_type_info.hpp(2 7) : warning C4103: 'x:\thirdparty\boost\boost\serialization\extended_type_info.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 1>..\..\..\ThirdParty\Boost\boost/config/abi_suffix.hpp(20) : warning C4103: 'x:\thirdparty\boost\boost\config\abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 1>..\..\..\ThirdParty\Boost\boost/serialization/extended_type_info.hpp(9 5) : warning C4103: 'x:\thirdparty\boost\boost\serialization\extended_type_info.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 1>..\..\..\ThirdParty\Boost\boost/config/abi_prefix.hpp(19) : warning C4103: 'x:\thirdparty\boost\boost\config\abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 1>..\..\..\ThirdParty\Boost\boost/serialization/extended_type_info_typei d.hpp(35) : warning C4103: 'x:\thirdparty\boost\boost\serialization\extended_type_info_typeid.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 1>..\..\..\ThirdParty\Boost\boost/config/abi_suffix.hpp(20) : warning C4103: 'x:\thirdparty\boost\boost\config\abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) 1>..\..\..\ThirdParty\Boost\boost/serialization/extended_type_info_typei d.hpp(143) : warning C4103: 'x:\thirdparty\boost\boost\serialization\extended_type_info_typeid.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) I saw discussion on this before and am wondering what is the solution? It only emits these warnings for x64 build and why not for x86 ? It only emits these warnings for one perticular project in my soluton whereas these headers are included in many projects. why? Thanks Shanti