Error code 4000 updating Iphone to IOS 14

I have noticed that many people are having issues trying to update their iPhones using iTunes to 14.0. I was forced to update my iTunes and I think the problem is in the latest iTunes. I can update the phone doing the over the air update and don’t get the error message. I also noticed the latest iTunes does not have a option for checking for updates. Apple please look into the issue and update iTunes. I only seem to have the problem with my phone. My other devices update fine through iTunes.

Yes, my problem was also solved by restoring the phone. But now I have the problem that without any knowledge about it, my backup was encrypted by apple on my harddrive on my computer, so I can’t restore all my files. I have tried 213 various combinations of passcodes but can’t unlock it. My phone, my computer that only I have access to, but can’t access my backup. I had important notes with bitcoin wallet information and made sure that the notes app by apple was syncing to iCloud but, discovered that it was not synced, only a few notes was on iCloud. All my bitcoin is therefore gone. It is apples fault because of their bad programing skills. This is my first apple product and my last. Apple you suck.

Now after removing my passcode for the encryption in iTunes and changing to a new one, iTunes is filling up all 8 gb of RAM when starting iTunes. Wtf is happening? New problem everyday. No peace of mind here.

I have this problem too on my IphoneX. I have the newest version of itunes and have tried to update my phone the whole day. I have restarted my phone and computer several times. Now I will try to change back my phone to original state as when I baught it and try it that way

I have Windows 10 PC, iPhone 8, and everything is up to date. Have restarted phone/PC/iTunes. Had to restore to update to 14.0. Now 14.1 comes out, same 4000 error code. Please help. Don't want to restore phone everytime I need to update.

Remove passcode and keep device unlocked until the update starts: https://forums.macrumors.com/threads/trying-to-update-to-ipad-os-14-itunes-giving-error-4000.2255178/