If you have an old ''Gramps XML'' database generated '''4 years ago''', then you could may have some difficulties to import them into last stable release ('''3.1.x'''). '''Gramps-1''' did not store '''[[Events_in_GRAMPS|event]]''' as primary object and did not use bsddb references. There was some limitations (''size, informations, encoding''), '''new Gramps versions''' tried to fix them.