Hey, good idee, I managed to get reimport file validated, but It does not seem to update values, do you think I would have to delete existing entries? I tried also to import on other instance, but that did not work because user ids a re different and I got no chance to assign to other (existing) users during import process.

here is a test of export from my own blog; i guess that one can modify the datesand then reimport (I will not do the reimport because it is my active data base); take attention to the date format because Odoo only accepts one (see exported format) id name history_ids/write_date __export__.blog_post_8027 Théâtre de Caen, 26 mars 2015, par Alain Lambert 04/02/15 01:10 PM 04/02/15 01:03 PM 04/02/15 01:03 PM __export__.blog_post_8026 Actualités musicales 04/02/15 12:54 PM 04/02/15 12:54 PM __export__.blog_post_8024 Opéra de Dijon, Auditorium, 29 mars 2015, par Eusebius 04/02/15 12:41 PM 04/02/15 12:41 PM 04/02/15 12:41 PM __export__.blog_post_8023 Actualités musicales 04/02/15 12:36 PM 04/02/15 12:36 PM

I don't think one need to delete existing date;however there are several fields for dates; I suppose that the field to change is named history_ids/write_date