I see in the changelog (http://www.boost.org/doc/libs/1_45_0/libs/serialization/doc/release.html) that files serialized with 1.42's binary serialization will have problems opening in 1.45. This is exactly what I'm experiencing. Luckily we have only used 1.42 in our project up to this point when we are testing for a release including boost 1.45, so we know all of our previous files were saved using 1.42. We should be able to automatically apply the fix_six fix when loading old files (I can tell by the filename when it's an old one). However I'm confused because fix_six bumps the version from 6 to 7, but in my copy of boost 1.42 serialization is already saving files w/ a library version of 7. Did 1.42 get patched to fix this issue already, or am I misunderstanding something? I found a recent thread where Robert Ramey asked someone to try trunk. I just did this and without the fix_six fix the files seem to be loading properly. Thanks, Jake