If your menus or widgets screens broke…
WordPress 3.0.5 was released at the same time as jQuery 1.5. Unfortunately, 1.5 has some backwards incompatible changes that appear to break a number of areas in the admin. The timing is awkward and it looks like it was us. It wasn’t.
There’s nothing we can do about this even for WordPress 3.1, which is freezing at jQuery 1.4.4.
If your theme deregisters jQuery and re-registers jQuery 1.5, then you’ll want to make sure that this change only applies for the frontend, i.e.
! is_admin(). (Or use the
wp_enqueue_scripts hook, which only fires for the theme-side.) This might not be obvious — if you’re enqueueing the latest jQuery from, say, Google’s CDN, you’ll be getting 1.5 suddenly, and things will break.
Someone should put together a quick plugin that restores and enforces the bundled jQuery in the admin. I’ll do it later tonight if no one else does.
Reference: #16508 and numerous support forum threads.