I have just upgraded from 1.5.2 to 2.3 (I know... quite late ;)
and I got the following error:
WordPress database error: [Duplicate entry '315-1' for key 1]
INSERT INTO wp_term_relationships (object_id, term_taxonomy_id) VALUES ('315', '1')
Upgrade Complete
Your WordPress database has been successfully upgraded!
But everything seems fine... the dashboard shows 2.3 and my blog seems to work fine... should I worry about that message?
I have done that on a test website and wonder if I can do it on my live one!
Thanks in advance!!
S.