iOS error codes

26 codes — tap one for its meaning, causes, and fix steps.

• 1015Cannot restore to a downgraded firmware version — iTunes detected an attempt to install an older iOS than what Apple currently signs.
• 1110USB configuration or device state error during restore.
• 1394Component or IPSW validation error — iTunes encountered an error validating part of the firmware bundle.
• 14Communication error during restore — the device connection was lost and the IPSW could not be fully written.
• 1600Device not in correct recovery or DFU mode for a custom restore.
• 1601USB driver or host-side communication failure during a recovery-mode restore.
• 1602Connection interrupted at the start of a recovery-mode restore — iTunes could not complete the initial handshake.
• 1604Unknown error during recovery-mode restore — device communication failed partway through.
• 1671Software update is downloading — this code is shown while the device is in the middle of downloading its update.
• 17Device could not be restored to the selected iOS version — the firmware is no longer being signed by Apple.
• 2001USB communication error during restore — the host-side USB chipset returned an unexpected error.
• 2009Device disconnected during restore — same as 4013 family but reported as a USB timeout by the host.
• 21Device in recovery mode and restore process failed — the restore was interrupted while the device was in recovery mode.
• 3004Cannot reach Apple servers — no network connection available during restore.
• 3014Network error contacting Apple servers during the restore process.
• 3194iTunes or Finder cannot contact Apple update servers — the IPSW cannot be validated.
• 40Internal error — the device IPSW installation encountered a problem during finalisation.
• 4000Unknown error — iTunes or Finder encountered an unspecified failure during the restore.
• 4005Restore failed — a communication error occurred between the device and the host during firmware write.
• 4013Device disconnected mid-restore — iTunes or Finder lost communication with the iPhone or iPad before the restore completed.
• 4014Same as 4013 — device disconnected during restore (alternate error number for the same hardware-communication loss).
• 4037Device is passcode-locked or encrypted and cannot be restored without unlocking first.
• 53iPhone hardware security check failed — Touch ID sensor or its secure connection to the Taptic Engine processor could not be verified after a repair.
• 56Component hardware failure detected — a core hardware component did not pass the device integrity check during restore.
• 9Device timed out or disconnected during restore.
• 9006Cannot download the software — the connection to Apple servers was interrupted while downloading the IPSW.