I have experienced this on Solaris and we just got a report that it also happens on Windows and Macosx:

Every now and then, running make asks me to reconfigure so I call configure again. Recently it is showing

  ERROR: /space/repos/jdk9/dev/build/macosx-x86_64-normal-server-fastdebug/spec.gmk is not up to date.
  Please rerun configure! Easiest way to do this is by running
  'make reconfigure'.
  make: *** [/space/repos/jdk9/dev/build/macosx-x86_64-normal-server-fastdebug/spec.gmk] Error 1

but running 'make reconfigure' shows the exact same words. This is happening on both macosx and Windows.

When does it work?

Thanks
Max