by Colin Fraser.
Aside from trying to revive a thread that is only partly related to your problem....
There have been major changes to the database from Moodle v1.9 to v3.1, so many that, as I understand it, the structure of the tables in the two databases are only related by a vague common heritage and I am not sure they are even using the same names. I would seriously suggest you get copies of v2.1, 2.4, and 2.8 and place them onto a stand-alone computer, each with different names and restore then backup in each version. Make sure they can each display all elements of the course you require. It may be that you will have to backup and restore into an existing course in, say, the v2.1 to v2.4 restore, then backup again to restore to the v2.8, then again to restore to the v3.1.
I know this is a pain, and it may be easier just to create a brand new course, but the jump from v1.9 to v3.1 is just too big a leap for the courses, or the Moodles to adequately handle.
Unless someone else has a better way of doing this, it is really the only way I know to make it work.