- Custom firmware can't be restored on a device with DFU Mode as the device is not in a pwned DFU Mode.
- APTicket problems if you try to restore to iOS 5.x in the DFU Mode.
- If truly stuck (even with an regular iTunes Restore), edit the hosts file and comment out the "guzzoni.apple.com" line so you can get valid blobs from Apple
- GetDeviceID: failed for iBoot (experienced on Windows 8)
See KB TA38633.
- Restart computer; change computer; reinstall system.
- If this error occured during an Apple TV restore, then unplug the Apple TV from the power cable, after you entered the recovery or DFU mode, and then try it again.
Device was not pwned (signature checks were not blocked). Custom firmware can't be restored. Can also happen when there's a problem with the IPSW.
iTunes tried to enter the Restore Mode, but the device turned back to the Recovery Mode. This can happen when updating an iPad 2 jailbroken with Saffron gets updated to iOS 5. In this case simply retry, as it is in Recovery Mode then anyway.
Missing system files or corrupt data in iTunes installation. Uninstall iTunes and Apple Mobile Device Driver, restart computer, and then install iTunes again. This error also occurs for iTunes in Windows 8 for reasons currently unknown.
Occurs when device is unplugged while the "iTunes will erase and restore your iPhone to iOS #.# and will verify the restore with Apple." dialog is shown. Check USB connections and try again.