Speaking of MELPA, I recently switched to their stable repository instead of their "regular" nightly build/snapshot repository after I accidentally ended up with a cider build that didn't want to playing ball. This is not a complaint - if you use nightly builds etc you know what you're getting yourself into - but it prompted me to switch over to using the stable package repository instead on those machines that I consider production machines. This of course require me to uninstall and reinstall a bunch of packages but that only took a few minutes.
Anyway, got update your ELPA/package.el configuration settings. And if you don't use ELPA, spend the ten minutes or so to switch from manual package management to ELPA. Of course, if you are using a different package manager, feel free to ignore all my ramblings and keep using that one instead.