What does the error message "your iphone cannot be updated error 4000" mean?

Hello Patrick,

Thanks for choosing the Apple Support Communities. If we understand correctly, you are unable to update due to an error. We can understand why you'd reach out for a resolution.

Here is a resource that can help.

If you see an error in Finder or iTunes on your computer

Cheers!

Most likely you have Windows 10 with the latest iTunes version, which has a problem losing the connection when the phone locks. The two workarounds (until Apple fixes it) are to downgrade iTunes to version 12.8 from https://itunes.com or temporarily disable your screen lock passcode.

Or update over the air by going to Settings/General/Software Update.