Hi, last time I tried to build Boost from develop (a few weeks ago) with MSVC, it worked perfectly. Now I get the following errors on two different Windows 7 machines with both MSVC14 CTP3 and MSVC12.3: boost/tools/build/src/build\virtual-target.jam:1099: in virtual- target.register-actual-name from module virtual-target error: Duplicate name of actual target: <pstage\lib>libboost_system-vc140- mt-1_57.lib error: previous virtual target { common%common.copy-libboost_system-vc140- mt-1_57.lib.STATIC_LIB { msvc%msvc.archive-libboost_system-vc140- mt-1_57.lib.STATIC_LIB { msvc%msvc.compile.c++-error_code.obj.OBJ { error_code.cpp.CPP } } } } error: created from ./stage-proper error: another virtual target { common%common.copy-libboost_system-vc140- mt-1_57.lib.STATIC_LIB { msvc%msvc.archive-libboost_system-vc140- mt-1_57.lib.STATIC_LIB { msvc%msvc.compile.c++-error_code.obj.OBJ { error_code.cpp.CPP } } } } error: created from ./stage-proper error: added properties: <asynch-exceptions>on error: removed properties: <asynch-exceptions>off boost/tools/build/src/build\virtual-target.jam:484: in actualize-no-scanner from module object(file-target)@14375 boost/tools/build/src/build\virtual-target.jam:134: in class@virtual- target.actualize from module object(file-target)@14375 boost/tools/build/src\build-system.jam:720: in load from module build-system boost\tools\build\src/kernel\modules.jam:289: in import from module modules boost\tools\build\src/kernel/bootstrap.jam:139: in boost-build from module boost\boost-build.jam:17: in module scope from module Does anyone have any idea what Boost.Build is trying to tell me?