Microsoft releases critical update for Windows Phone 8.1 Preview for Developers program

Those who use the Windows Phone 8.1 Preview for Developers, should have an update waiting for you to download and install. The update has the 8.10.14192.280 build number and should take around five to ten minutes to install. Microsoft calls it a "Critical Update" because it is necessary for it to test its update systems.

If you're in the Windows Phone Preview for Developers, you should receive an automatic notification when the update is ready for installation. You could also head to Settings > Phone Update > Check for Update and manually install the update. The Preview for Developers program gives members the ability to see Windows Phone OS updates before they are sent out to the public. For developers, this gives them the opportunity to make sure that their apps run smoothly on a new build of Windows Phone.

"This update contains our usual scope of fixes and improvements. We're requiring this update so we can continue to test our update systems. The update will show as a "critical update" on your phone." -Microsoft

While the update itself wont bring any new features, its likely making way for the next update by fixing something or adding some background features, so its advised that you install the update as soon as you can.

source - Windows Central