Back in 1.53.0, I could do the following: ./bootstrap.sh (cd tools/bcp; ../../b2) bin.v2/.../bcp build filesystem .../temp Then in .../temp run ./bootstrap.sh and ./b2 to build just filesystem (or whatever else I copied). In 1.54.0, the copy doesn't build: brs% ./b2 Building the Boost C++ Libraries. /auto/tmpfs/temp/tools/build/v2/build/targets.jam:397: in find-really *** argument error * rule project.is-registered-id ( id ) * called with: ( ) * missing argument id /auto/tmpfs/temp/tools/build/v2/build/project.jam:600:see definition of rule 'project.is-registered-id' being called /auto/tmpfs/temp/tools/build/v2/build/targets.jam:457: in class@project-target.find /auto/tmpfs/temp/tools/build/v2/build/targets.jam:841: in resolve-reference /auto/tmpfs/temp/tools/build/v2/build/targets.jam:858: in targets.generate-from-reference /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1245: in generate-dependencies /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1302: in class@basic-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:757: in generate-really /auto/tmpfs/temp/tools/build/v2/build/targets.jam:729: in class@main-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:272: in class@project-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:874: in targets.generate-from-reference /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1245: in generate-dependencies /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1302: in class@basic-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:757: in generate-really /auto/tmpfs/temp/tools/build/v2/build/targets.jam:729: in class@main-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:874: in targets.generate-from-reference /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1245: in generate-dependencies /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1302: in alias-target-class.generate /auto/tmpfs/temp/boostcpp.jam:391: in build-multiple /auto/tmpfs/temp/boostcpp.jam:353: in class@top-level-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:757: in generate-really /auto/tmpfs/temp/tools/build/v2/build/targets.jam:729: in class@main-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:874: in targets.generate-from-reference /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1245: in generate-dependencies /auto/tmpfs/temp/tools/build/v2/build/targets.jam:1302: in alias-target-class.generate /auto/tmpfs/temp/boostcpp.jam:391: in build-multiple /auto/tmpfs/temp/boostcpp.jam:353: in class@top-level-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:757: in generate-really /auto/tmpfs/temp/tools/build/v2/build/targets.jam:729: in class@main-target.generate /auto/tmpfs/temp/tools/build/v2/build/targets.jam:272: in class@project-target.generate /auto/tmpfs/temp/tools/build/v2/build-system.jam:707: in load /auto/tmpfs/temp/tools/build/v2/kernel/modules.jam:289: in import /auto/tmpfs/temp/tools/build/v2/kernel/bootstrap.jam:139: in boost-build /auto/tmpfs/temp/boost-build.jam:17: in module scope