From: Boost-build <> On Behalf Of Andrzej Krzemienski via Boost-build
Sent: 22 May 2022 14:03
Cc: Andrzej Krzemienski <>
Subject: [Boost-build] Help in fixing my b2


Hi Everyone,

I was redirected to this email list for help with b2. I am trying to build the docs for Boost.Optional, and in all honesty, I do not know if I have a problem with b2 o bjam or BoostBook or QuickBook or QuickDoc or xsltproc.


First, I am getting an error message:


error: mismatched versions of B2 engine and core
error: B2 engine (b2) is 4.4.1
error: B2 core (at /home/andrzej/Repos/boost/tools/build/src) is 4.9-git


This used to work until I recently made a `git pull --rebase` on Boost repo, which apparently put out of sync components "B2 engine" and "B2 core", whatever they may be. I have a `b2` in my /usr/bin -- I do not know where from, as I didnt know it comes with Fedora distributions (I thought it was Boost internal tool) -- of version 4.4, and I have another one in tools/build of version 4.9. I have been instructed to "rebuild the b2 engine executable", but I do not know how to do it, and which executable, as apparently I have got two. I would appreciate any detailed instructions on how to do it.


Cd to your /home/andrzej/Repos/boost/tools/build


>b2 -v should show your current version.  (or >b2 –version)


>b2 -a should build the newest version in this folder.


You should get an b2.exe and bjam.exe, probably in a /bin folder.


>b2 -v will show which version it is


You can copy this to your usr/bin


Finally you could grep to find all versions of b2.exe and bjam.exe and check each file datestamp and delete all old one and replace, if necessary with new version.


Then you should have everything back in sink.