The Cupertino-based company however had to temporarily pull the software update for select older iOS devices after reports of a bug in iOS 9.3 causing the older devices to get 'bricked'. It rectified the issue in less than a week, re-releasing the update. Separately, the company had acknowledged an issue in Safari and other apps that caused iPhone and iPad apps running iOS 9 or above to freeze or crash when users tried to open a link on Safari or other app, and promised an update. This latest update addresses that issue, which is speculated to be related to Universal Links, a feature that Apple first introduced with iOS 9.
The official changelog for the iOS 9.3.1 says, "Fixes an issue that caused apps to be unresponsive after tapping on links in Safari and other apps." Unfortunately, the changelog doesn't mention any further changes in the iOS 9.3.1 update.
As always, iOS updates are available over-the-air (OTA) on your device (Settings -> General -> Software Update) as well as via iTunes on your PC or Mac.
To recall, Apple with iOS 9.3 had added Night Shift, which was the biggest highlight of the update. The feature altered the tone and blue light emission of the device's display to prevent eye strain. The company had even claimed that Night Shift could improve a person's sleep quality while also offering some other health benefits.
Some of the enhancements in the update included improvements to News, which now had "top stories" to Apple News. Apple had also pushed some improvements to the visualisation of health data collected by the Health app.