For the past month or so, I've been unable to backup my iPhone using iTunes.
Every time I try, I'm told that the phone is "disconnected":
What could be causing this?
I've tried different USB cables and different USB ports, but the result is always the same.
I'm using OS X 10.10.3, iTunes 18.104.22.168, and iOS 8.3.
The procedure I'm using is the obvious one: launch iTunes; connect the iPhone; choose the iPhone in iTunes; press "Sync".