Hi, I'm trying to update the Fedora rawhide package to Boost 1.59.0 and the build fails with the output below (ignore the MPI warnings). We build with the following in user-config.jam: # This _adds_ extra python version. It doesn't replace whatever # python 2.X is default on the system. using python : 3.4 : /usr/bin/python3 : /usr/include/python3.4m : : : : m ; Is that comment no longer true? Did something change in Boost 1.59.0 so that that line now sets the only allowed python version? I can make the build work with the following but I'd like to understand the change: using python : 2.7 : /usr/bin/python2 : /usr/include/python2.7 : : : : ; using python : 3.4 : /usr/bin/python3 : /usr/include/python3.4m : : : : m ; Build failure: + echo ============================= build serial ================== + ./b2 -d+2 -q -j4 --without-mpi --without-graph_parallel --build-dir=serial variant=release threading=multi debug-symbols=on pch=off python=2.7 stage MPI auto-detection failed: unknown wrapper compiler mpic++ Please report this error to the Boost mailing list: http://www.boost.org You will need to manually configure MPI support. /builddir/build/BUILD/boost_1_59_0/tools/build/src/build/feature.jam:494: in feature.validate-value-string from module feature error: "2.7" is not a known value of feature <python> error: legal values: "3.4" /builddir/build/BUILD/boost_1_59_0/tools/build/src/build/property.jam:276: in validate1 from module property /builddir/build/BUILD/boost_1_59_0/tools/build/src/build/property.jam:302: in property.validate from module property /builddir/build/BUILD/boost_1_59_0/tools/build/src/build/build-request.jam:216: in convert-command-line-element from module build-request /builddir/build/BUILD/boost_1_59_0/tools/build/src/build/build-request.jam:154: in build-request.from-command-line from module build-request /builddir/build/BUILD/boost_1_59_0/tools/build/src/build-system.jam:583: in load from module build-system /builddir/build/BUILD/boost_1_59_0/tools/build/src/kernel/modules.jam:295: in import from module modules /builddir/build/BUILD/boost_1_59_0/tools/build/src/kernel/bootstrap.jam:139: in boost-build from module /builddir/build/BUILD/boost_1_59_0/boost-build.jam:17: in module scope from module