Hello David, DA>> And you think this is a bug in Boost code? Can you post a DA>> reproducible test case? DA>> I bet you didn't use Boost.Build to create your extension module, as DA>> recommended in the Boost.Python documentation. You probably are DA>> linking with multiple copies of the runtime. VP> Now that you've mentioned that, I went and stuffed the above code VP> right into \libs\python\example\getting_started1.cpp, then bjammed it. VP> Got the same assertion failure in Python session. Does this count? On the second thought, I replaced boost_python.dll built with IDE projects with boost_python.dll built by bjam, and the assertion disappeared. Oh well. Then I put boost_python_debug.dll built with IDE into the app dir (renaming to boost_python.dll, of course), and tried again. No assertion. Putting back release version of the dll brought the failure back. So, the assertion only appears when using release version built using \libs\python\build\VisualStudio\boost_python.dsw I don't claim that it is Boost code that has an error---but surely there _is_ a bug somewhere in there? Maybe MSVC projects, maybe MSVC itself :) . -- Best regards, Vladimir mailto:pvv@ugnn.ru