Apple has temporarily stopped offering the iOS 9.3 update for older devices like the iPad Air and earlier and the iPhone 5s and earlier due to installation issues some users have experienced. On older devices, iOS 9.3 requires users to input the Apple ID and password originally used to set up the device, which can lead to the device becoming stuck at the Activation Lock screen if the original account information can't be recalled.
In a statement given to iMore, Apple says it is working on a fix and plans to issue a new version of iOS 9.3 in the next few days. Customers with an affected device who attempt to download iOS 9.3 during this time will not be able to install the update as Apple has stopped signing it.
Updating some iOS devices (iPhone 5s and earlier and iPad Air and earlier) to iOS 9.3 can require entering the Apple ID and password used to set up the device in order to complete the software update," an Apple spokesperson told iMore. "In some cases, if customers do not recall their password, their device will remain in an inactivated state until they can recover or reset their password. For these older devices, we have temporarily pulled back the update and will release an updated version of iOS 9.3 in the next few days that does not require this step."
For customers who have already installed iOS 9.3 and have gotten stuck at the Activation Lock, Apple has published a support document with steps on how to solve the issue. Apple recommends removing Activation Lock via iCloud or attempting to enter an Apple ID or password through iTunes.
Update: Apple has released a new build of iOS 9.3 for the iPad 2 and may be planning to roll out updates for additional devices. Apple has not yet resumed signing iOS 9.3 for affected devices.