How to fix the device could not be restored − An unknown error occurred (9) iTunes error (iPad)

It is possible that the USB port in which the USB (lightning) cable is currently plugged in is broken, which weakens the link between the computer and the mobile device. Or, the part of the motherboard, which reads the input from the USB port may be broken.

Since motherboards have more than one USB port at their disposal, plug the cable in another USB port and try again.

The main reason for iTunes error 9 is an outdated iTunes version. What's worse, the current version can have bugs if iTunes files were removed by another software. To fix this unknown error, and many others, you need to update iTunes. Even though updates are installed automatically, or a warning popup appears when you open iTunes, sometimes, this may not always be the case. Sometimes, you need to check for updates manually, through iTunes, or on Apple's website.

To check for updates manually:

1. Open the iTunes app;
2. Click on Help and select Check for updates.
   
   
   
   

Or, you can follow the instructions in the video demo, below:

In order for any computer to run, a set of processes need to run in the background, in charge of various tasks (let you play a game, connect to the Internet, and more). If one of those processes isn't executed, isn't executed correctly, or is stuck executing, your operating system will return an error. Usually, restarting the computer is all you need to do to resolve such issues, and fix the iTunes 9 error code. Restart your computer and try restoring your device again.

Note: To make restarting your computer more effective, you may want to do a "power-cycle" to your computer, i.e. drain all it's accumulated power. If you use a desktop computer, unplug it from the power cord, and plug it back it. If you use a laptop, and its battery is removable (i.e. you can remove the battery without opening the laptop, remove the battery and insert it again.

In order for iTunes to be able to restore your device, it needs to read all the data on your iOS device. If it can't or if it won't read all the data, it won't be able to update your device, or restore it. It is possible that unstable connection between the computer and the iOS device is responsible for this iTunes error.

Disconnect and reconnect the USB cable on both ends and then try again, which will reconnect the plates of the lightning cable with the USB port of your computer, and the lightning port of your iOS device.

It is possible that the current firewall and antivirus settings are causing this issue. To test this, try disabling them and check if you still get the error message.

If you don't get an error message, it's time to access the firewall and the antivirus settings and check how they are configured.

To disable the Windows Firewall:

1. Go to the start menu and type Windows Firewall;
2. Click on Windows Firewall and then Turn Windows Firewall on or off;
3. Click on Turn off Windows Firewall (not recommended) under Private and Public networks:
   
   

To enable the Windows Firewall:

1. Go to the start menu and type Windows Firewall;
2. Click on Windows Firewall and then Turn Windows Firewall on or off;
3. Click on Turn on Windows Firewall for both Private and Public networks;
   
   

Maybe dust lumps that have accumulated on the computer's USB port, or, very likely on the device's lightning port, are responsible for the error message, as it interrupts the strong link between your device and the computer. Double-check and clean the ports on both ends and try again.

Grab a tiny cotton swab, sip a small amount of rubbing (isopropyl) alcohol on it and then gently clean the USB and lightning ports. Wait until the alcohol evaporates (usually up to a minute) and then try updating your device again.