Currently I see: D:/data/boost/boost/tools/build/src/tools\msvc.jam:1388: in configure-really *** argument error * rule generate-setup-cmd ( version : command : parent : options * : cpu : global-setup ? : default-global-setup-options : default-setup ) * called with: ( 14.16.27023 14.11.25503 : D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64 : D:\compilers\visual studio\2017\VC\Tools\MSVC\14.11.25503\bin\HostX64 : <command>D:\compilers\visual studio\2017\VC\Tools\MSVC\14.16.27023\bin\Hostx64\arm\cl.exe <command>D:/compilers/visual studio/2017/VC/Tools/MSVC/14.11.25503/bin/HostX64/x64/cl.exe : i386 : : x86 : vcvars32.bat ) * extra argument 14.11.25503 D:/data/boost/boost/tools/build/src/tools\msvc.jam:1003:see definition of rule 'generate-setup-cmd' being called D:/data/boost/boost/tools/build/src/tools\msvc.jam:393: in configure D:/data/boost/boost/tools/build/src/tools\msvc.jam:345: in msvc.init D:/data/boost/boost/tools/build/src/build\toolset.jam:44: in toolset.using D:/data/boost/boost/tools/build/src/build\project.jam:1104: in using C:\cygwin64\home\John Maddock\user-config.jam:46: in modules.load D:/data/boost/boost/tools/build/src\build-system.jam:255: in load-config D:/data/boost/boost/tools/build/src\build-system.jam:453: in load-configuration-files D:/data/boost/boost/tools/build/src\build-system.jam:607: in load D:\data\boost\boost\tools\build\src/kernel\modules.jam:295: in import D:\data\boost\boost\tools\build\src/kernel/bootstrap.jam:139: in boost-build D:\data\boost\boost\boost-build.jam:17: in module scope Master is fine BTW. Best, John. --- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus