Hello group! We are upgrading boost from version 1.34.1 to 1.43.0. A quick test revealed that after the upgrade our binary archives cannot be loaded anymore. It seems like the type of the class id was changed from int to short making the old archive from 1.34.1 incompatible to our current application using 1.43.0. Is this a bug or expected behavior? How does boost serialization treat backwards compatibility? Will archives created by earlier versions of the library be still loadable? Do different archives behave differently in this regard? We do not really require backwards compatibility. I would just like to know what to expect. Thanks you. Markus Henschel Lead Programmer YAGER Development GmbH Pfuelstraße 5 10997 Berlin Germany www.yager.de<http://www.yager-development.com/> Sitz der Gesellschaft: Berlin | Geschäftsführer: Timo Ullmann, Uwe Beneke Amtsgericht Berlin-Charlottenburg | HRB 78261 | USt-ID-Nr. DE 212404124