On the covered Apple iPhone or iPad, 9 means Apple's article lists 9 with the errors to try again on: it says to try updating the device again, and to check third-party security software for errors 2, 4, 6 and 1611. First, try the update again.
Try in this order
0 of 8 completedWhat to do first
ReversibleTry the update again.
Correct only the documented fault domain
ReversibleApple's only step for error 9 is to try the update again; Apple's page notes it can appear when the device disconnects during the update or the computer loses its connection to it during a restore. If it repeats, check the cable and port and any security software, and if it still fails Apple says to consider a hardware fault.
Do not touch the cable during the update
ReversibleError 9 can appear when the device disconnects during the update or the computer loses its connection to the device in a restore, so leave the cable still and keep the laptop awake and on power.
Run the update again
ReversibleApple's own step for error 9 is to try the update again; most owners clear it on the second attempt.
Plug straight into the computer
ReversibleUse the cable that came with the device and a port on the computer itself, not a keyboard or hub, so the connection does not drop.
Check security software
ReversibleApple groups error 9 with the errors that security software can interrupt, so pause third-party security software for the update and turn it back on afterwards.
Disconnect everything else from the computer
ReversibleUnplug other USB devices, docks and hubs, leaving only the iPhone or iPad connected. Security software and extra USB devices are a common reason for error 9, and removing them narrows the cause.
Update the security software or pause it
ReversibleCheck for updates to your antivirus or endpoint protection, and pause it briefly while you retry the restore. Turn it back on straight afterwards, and add the Apple app to its allowed list if it keeps interfering.
Evidence ledger
Sources behind this answer
Exact questions
Common questions about “Apple iPhone or iPad code 9”
What does 9 mean on a Apple iPhone or iPad?+
Apple's article lists 9 with the errors to try again on: it says to try updating the device again, and to check third-party security software for errors 2, 4, 6 and 1611.
Why does error 9 appear halfway through an iPhone update?+
The connection between the phone and the computer dropped. A loose cable, a hub or a sleeping computer are the usual reasons.
Is error 9 the same as error 4013?+
They are listed together in an Apple article for restores and both mean the connection was interrupted, but Apple gives them separate numbers, and error 9 is also grouped with security-software errors.
What does error 9 mean?+
Apple lists it among errors where the connection between the device and the computer was interrupted, often by the cable, the port or security software.
Is the device damaged?+
Usually not; the restore or update was cut short, and trying again on a clean connection often succeeds.
Should I use a different computer?+
If the restore fails twice on one computer, a second computer is the quickest way to find out whether the first one is the cause.
Does the cable matter?+
Yes, an Apple or certified cable in good condition matters, since a bent or worn cable breaks the link.