Woe is me till I find the time to fix it.
Please stand by.
I’m asking about it on the wp support forum.
Update: And we’re back. The way I fixed it: running this SQL:
-- update DBPREFIX with your own. It may be "wp_" update DBPREFIX_posts set post_type='post' where post_parent=0;
My theme is not really 2.1 compatible, so I had to do some other hacking as well. When I had everything displaying on the home page, ALL BLOG POSTS were displaying. That’s too many posts. I’m just glad nothing was lost.
Kids, don’t rush your software upgrades right before bedtime. It’s the wrong thing to do.