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I lost about 700 contacts off my iPhone 8.

I lost about 700 contacts off my iPhone 8. I have about 386 still there but I have no idea where they went. I have all of them on my laptop (windows based) but when tried to sync with iTunes it tried to update my phone I received a code 4000.

iPhone 8, iOS 14

Posted on Dec 30, 2020 12:42 PM

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Question marked as Top-ranking reply

Posted on Dec 30, 2020 12:43 PM

Error 4000 is an undocumented error code (at least publicly undocumented). It means that the connection between the phone and iTunes was interrupted in the middle of a sync or update activity. In the past this might have been caused by a flakey USB port, an antivirus or a firewall. However, there is a new cause of this error that is the result of a bug in iTunes for Windows that requires the phone not be locked during the update. So first check your antivirus and firewall (temporarily disable them), but if that doesn’t fix it there are three workarounds for the bug:


  • Update over the air, by going to Settings/General/Software Update
  • Downgrade iTunes to version 12.8 if you can find a copy - try https://apple.com/itunes
  • Temporarily disable the screen lock passcode on the phone before updating using iTunes on Windows


Note that this error should only be a problem for updates; if you are restoring iOS rather than updating it should not occur.

1 reply
Question marked as Top-ranking reply

Dec 30, 2020 12:43 PM in response to tjmoran1976

Error 4000 is an undocumented error code (at least publicly undocumented). It means that the connection between the phone and iTunes was interrupted in the middle of a sync or update activity. In the past this might have been caused by a flakey USB port, an antivirus or a firewall. However, there is a new cause of this error that is the result of a bug in iTunes for Windows that requires the phone not be locked during the update. So first check your antivirus and firewall (temporarily disable them), but if that doesn’t fix it there are three workarounds for the bug:


  • Update over the air, by going to Settings/General/Software Update
  • Downgrade iTunes to version 12.8 if you can find a copy - try https://apple.com/itunes
  • Temporarily disable the screen lock passcode on the phone before updating using iTunes on Windows


Note that this error should only be a problem for updates; if you are restoring iOS rather than updating it should not occur.

I lost about 700 contacts off my iPhone 8.

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