Dear Peter and All, Thank you for your last message. Finaly, when making all the investigations I could, the result is that the problem doesn't come from the upgrade... But from the database itself... The database under our production OTRS is OK, but when we make a dump of the database and import it in an other instance of OTRS, then the message Erreur: Need SystemAddressID! Appears. And, finaly, it's not only when making a queue a subqueue of another, but when trying to modifiy any option of any queue (name, subqueue, group, options and so on...). I think our database is corrupted {:o( Maybe the problem is the way I make the dumps... I use mysqldump --add-drop-table -u root -p otrs > otrs.bkp Do you have any way idea or way to recover our database??? Many thanks in advance for any light, Philippe Roth