User profile for user: DanS64
DanS64 Author
User level: Level 1
8 points

iPhone will not update thru iTunes

I had this problem years ago with my iPhone 5. My iPhone 8 will not update the iOS thru iTunes. In the logs I have 2 errors - 4000 and 4037. iTunes gets the iOS software and the iPhone does a backup. I enter my passcode as requested and the system goes thru the prep and then iTunes reports the 4000 error.


Years ago there was a board I went to and it told me to delete certain files and then do an update after that and it worked. I have no issues doing the update directly thru the phone - I have the most recent iTunes and my iPhone routinely backs up when connected.


Every other board that I've gone to has suggested things that I've done already without success. This happened right after moving to iOS 14.2 - Any help is appreciated.

Windows, Windows 10

Posted on Dec 20, 2020 1:24 PM

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User profile for user: Lawrence Finch
Lawrence Finch
User level: Level 10
229,474 points

Posted on Dec 20, 2020 2:32 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.

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User profile for user: Lawrence Finch
Lawrence Finch
User level: Level 10
229,474 points

Dec 20, 2020 2:32 PM in response to DanS64

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.

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iPhone will not update thru iTunes

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