When I try to backup my iPhone 6 on a MacBook Pro I receive the following message: iTunes could not back up the iPhone XXX because the iPhone disconnected.
Everything looks normal for a while but then....
iTunes 12.4.0.119
iPhone 6 iOS 9.3.2
Posted on Jun 1, 2016 12:11 PM
Q: iPhone disconnecting from iTunes
If you can't make an iTunes backup of your iPhone, iPad, or iPod touch - Apple Support