Error code

iOS 9

IOS9
System Error Code· A POSIX/system errno returned when a system call fails.

What it means

Device timed out or disconnected during restore..

How to fix it

  1. Force restart the device and put it into recovery mode manually before retrying.
  2. Disconnect and reconnect with a different cable.
  3. Temporarily disable antivirus and firewall.
  4. Try on a different computer.

Not affiliated with iOS. Answer summarized from the manufacturer's manual linked above; consult that source for the authoritative procedure.