The version of iOS running on your iPhone or iPad does not support wirelessly updating to this version of iOS.
After being burned a few times by iOS updates crippling older devices (iOS 7 on iPhone 4 comes to mind), I decided to keep my iPad Air 2 on iOS 9 indefinitely.
Having seen stellar reviews of iOS 12 and how it has great performance across all supported devices, I decided to finally update my Air 2. I got the iOS 12 update notification, and after going Settings->General->Software Update I am greeted with the message on the post title. It further says “Please connect your device to iTunes on a computer to update to the latest software.”
So apparently I am forced to connect my iPad to a computer with iTunes to do the update? Does anyone know a way around that?