Unknown error (-1) iPhone 5
Hello! Tell me what to do!I began to update iPhone 5, locked to ATT operator. I wanted to upgrade to iOS 8.2 to 8.3, but then has got out unknown error (-1), what to do? Thank you
Take a look at these articles:
Resolve iOS update and restore errors in iTunes - Apple Support
Get help with iOS update and restore errors - Apple Support
Also, I'd suggest to contact AT&T support and ask for help.