OK so I found :
the error is a user_id error that conflicts with SQL constraints....... not a structural problem....
Oct 2 17:54:13 sd173 roundcube: DB Error: [7] ERROR: duplicate key violates unique constraint "contacts_pkey" (SQL Query: INSERT INTO contacts (user_id, changed, del, "vcard", "name", "email", "firstname", "surname", "words") VALUES (1001, now(), 0, 'BEGIN:VCARD^M VERSION:3.0^M N:qsd;qsd;;;^M FN:qsd qsd^M EMAIL;TYPE=INTERNET;TYPE=HOME:qsd@qsd.fr^M END:VCARD', 'qsd qsd', 'qsd@qsd.fr', 'qsd', 'qsd', ' qsd qsd@qsd.fr')) in /home/roundcubemail-1.0.1/program/lib/Roundcube/rcube_db.php on line 467 (POST /webmail/?_task=addressbook&_orig_source=0?_task=addressbook&_action=save)
I don't know yet how to correct that ... but here is the problem.