For some reason, my sidebar is not working properly. Everything was fine after upgrading, so that is not the problem. Now, my widgets are at the bottom of the main page instead of on the right. And when you click on a post, then the widgets on the post page are correct.
Check ALL the posts on that front/main page… especially where you see that everything is getting bold – doesn’t that tell you that you messed up at least one post’s code?