As of today, if you run: ./bootstrap.sh ./bjam in trunk, then the build will immediately stop on any error. The same is true with bootstrap.bat on Windows. The previously behaviour was to continue building other targets that don't depend on the failed one. The "keep going" behaviour has some good properties, for experienced users, but for new users of Boost, it was sufficiently confusing: - It's easy to miss compilation error, and then you learn that something has failed at the end of build - There's no clean at-the-end summary of what has failed, and what to do - Some users don't even know how to capture build output for further analysis, and the build output, with all the errors, can easily overflow scrollback buffers of console windows The new behaviour is implemented by writing an option into project-config.jam. Anybody who wants the old behaviour can edit that file, or pass --keep-going on the command line. The change does not affect regression tests. - Volodya