Don't update until it all shakes out.
Apple's latest version of its mobile operating system—iOS 10—is now out in the wild. If you get a notification to install it over the air, don't. It could mess up your phone.
As users are reporting on Twitter, the current iOS 10 update has the potential to "soft brick" devices it is installed on. This means that the affected iPhone or iPad will not work until it is plugged into a computer and restored with iTunes, but not for good. A serious inconvenience at best, a way to lose a bunch of your data at worst.
tried to update to iOS 10 and now i have a really expensive brick i get to carry around for the rest of the day.
The best way to avoid the problem is simply to not install iOS 10 until Apple issues a version of the update that doesn't run the risk of putting your device out of commission. We will update this post when the coast is clear.
We experienced a brief issue with the software update process, affecting a small number of users during the first hour of availability. The problem was quickly resolved and we apologize to those customers.