Error code 4000 after multiple attempts to update my iPhone

See this discussion about iOS14 Error 4000 --> https://discussions.apple.com/thread/251804526

which was recommended by an Apple Community Specialist in this post --> https://discussions.apple.com/thread/252380437?answerId=254515885022#254515885022

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. I think this has been finally fixed in the latest iTunes update, so try getting that from https://itunes.com/. If not 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 ran into this same problem. I was able to work around the problem by doing this:

1. In iTunes, hold down the shift key and then click the "Update" button
2. Go to C:\Users\seitz\AppData\Roaming\Apple Computer\iTunes\iPhone Software Updates
3. Select the ".ipsw" file

My iPhone update then completed successfully.

I elected to update my phone via Wi-Fi and pulled in the update. Then I connected my phone to my laptop and opened iTunes. I then clicked the update button and it read the phone was up to date. Then I synced my phone to the cloud and laptop and then back it up also. Done, problem solved..

How do I clear a4000 error code

I am not experienced enough to go through all those channels, can someone please help me

We will try it later thank you for your response

I do not have (or see, and I searched for it too) the "Seitz" file, therefore I cannot complete the suggested fix. Thank you.