Upgraders are taking to social media to complain that some "over the air" iOS 10 updates are failing, necessitating a full restore for an afflicted device through iTunes [update: now fixed].
Update: Apple said Tuesday afternoon that it had fixed the problem and over-the-air updates should install normally.
The failure to properly update to iOS 10 appears to be related to an incomplete or corrupted download. Some early speculation existed that iOS 10.0.0 may be getting downloaded, with an immediate behind the scenes update to iOS 10.0.1 being the culprit, but that does not immediately appear to be the case, according to Apple support.
At this time, there does not appear to be any outright failures in the update process, leading to utterly dead devices. After being plugged into iTunes when greeted with the failure message, iOS devices are either finishing the update to iOS 10.0.1, or reverting back to 9.3.5, suggesting more than one possible problem leading to the forced restore through iTunes.
Users without a backup either locally in iTunes or in the cloud are losing iPad-stored data as a result of the iTunes restoration.
AppleInsider has spoken with Apple regarding the matter and was told that support personnel were already looking into the problem. We were told that the problem may be related to a timed-out download as a result of ISP issues in conjunction with Apple software distribution system loads.
As with any update, AppleInsider recommends backing up the device prior to starting the process. Additionally, updates on mission-critical hardware should generally be postponed until the process is known to be stable.