Both the release & trunk version of MPI no longer compile on Microsoft Windows with Microsoft Compute Cluster Pack. With 1.46.1: ===============MPI Auto-configuration=============== Found Microsoft Compute Cluster Pack: C:\Program Files\Microsoft Compute Cluster Pack MPI build features: <include>/C:/Program Files/Microsoft Compute Cluster Pack/Include <address-model>64:<library-path>/C:/Program Files/Microsoft Compute Cluster Pack/Lib/amd64 <library-path>/C:/Program Files/Microsoft Compute Cluster Pack/Lib/i386 <find-static-library>msmpi <toolset>msvc:<define>_SECURE_SCL=0 MPI launcher: "C:\Program Files\Microsoft Compute Cluster Pack\Bin\mpiexec.exe" -n ==================================================== .... Currently: D:/src/boost-release-test/boost/tools/build/v2/tools\mpi.jam:249: in mpi.init rule path.make unknown in module mpi. D:/src/boost-release-test/boost/tools/build/v2/build\toolset.jam:38: in toolset.using D:/src/boost-release-test/boost/tools/build/v2/build\project.jam:888: in using C:\Users\KTC\user-config.jam:5: in modules.load D:/src/boost-release-test/boost/tools/build/v2\build-system.jam:257: in load-config D:/src/boost-release-test/boost/tools/build/v2\build-system.jam:399: in load-configuration-files D:/src/boost-release-test/boost/tools/build/v2\build-system.jam:555: in load D:\src\boost-release-test\boost\tools\build\v2/kernel\modules.jam:283: in import D:\src\boost-release-test\boost\tools\build\v2\kernel\bootstrap.jam:142: in boost-build D:\src\boost-release-test\boost\boost-build.jam:17: in module scope KTC Created ticket on Trac: <https://svn.boost.org/trac/boost/ticket/5618>