[@sd17 Participant 9 years, 6 months ago]

I believe this is because of DB differences between phpBB 3.0x and 3.1x.

Current import only supports phpBB 3.0x

I was able to get rid of the error messages by creating the columns it complains about.

You can also try this: https://bbpress.trac.wordpress.org/attachment/ticket/2716/2716.1.diff