BuddyPress.org

OK, found the problem. I’m running BP on a blog other than blog_id=1. Apparently I had made the change to BP_ROOT_BLOG in a core file (not sure why). So when the new files were loaded, and bp-core-catchuri.php tried to parse the URL, it was getting hung up on the fact that the current blog was not (so it thought) the BP blog.

I set the constant in a plugin, where it belongs, and everything is hunky dory now.