Apple has just released iOS 9.2.1, the first bug fix update since iOS 9.2 was released and the third update for iOS 9 overall. It's available as an over-the-air download or through iTunes for everything that supports iOS 9: the iPhone 4S or newer, the iPad 2 or newer, all flavors of the iPad Mini, the iPad Pro, and the fifth- and sixth-generation iPod Touches.

Apple's release notes are less forthcoming than they usually are. iOS 9.2.1 provides non-specific security and bug fixes as well as "a fix for an issue that could prevent the completion of app installation when using an MDM (Mobile Device Management) server."

Last week, Apple acknowledged a time zone-related bug in the iPhone 6S and 6S Plus that could keep the battery percentage indicator from updating properly when users manually change the time zone or travel from one time zone to another. We've asked Apple whether iOS 9.2.1 includes a fix for that issue, but in the meantime Apple's support document provides an official workaround. We'll update this article if the company responds and if the update fixes any high-profile security issues (the notes about specific security fixes post to this page and generally take an hour or two to show up).

Update: Apple tells us it's still looking into the battery percentage indicator issue and that there's no fix available in 9.2.1. The security content of the update has also been posted here.