After you exit Minecraft, the loading screen stays black and won't change. This will force you to uninstall Minecraft, which removes all worlds, deletes all resource packs, makes all marketplace items have to be redownloaded, and resets your settings (FOV, brightness, controls, etc). I've had to uninstall Minecraft 5+ times today to play. This is by far the worst bug I have ever encountered. Please fix this in the next hotfix.