iOS 14.0.1 error 4000


Sep 29, 2020
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Hi all! I’m new here.
Having problems updating to 14.0.1 on my windows 8.1 laptop. I think I’ve tried every solution possible but maybe I’ve missed something.
Here’s the history:

I updated iTunes to the latest version. I restarted the pc. i downloaded the full iOS in iTunes. I click update, enter the passcode, it backs up, says extracting software, says preparing iPhone for update, then I get error 4000.

Here’s everything I’ve tried:
I restarted my pc and did full shutdowns/reboots a few times. I turned passcode off on my phone. I turned the screen auto lock to never. I restarted my iPhone. I did a hard reset. all apps are cleared. I cleared the phone RAM. no third-party apps are running. no VPNs. Norton is 100% disabled on my pc. PC processes/processor/RAM are all near zero in the task manager. quick startup is off. the PC’s 8.1 software is 100% up to date. i used all three of my laptop USB ports, and three different lightning cables including a brand new one, and it keeps failing with a 4000 error, even though with the three cables and all three USB ports, my phone can back up and sync fine.

I don’t know what else to do.

Have I missed something?

I could do the delta over WiFi but who knows, that may fail too. I prefer the full iTunes update anyway.

Thanks for any help!



Apple Watch Champion
Jan 10, 2013
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Welcome to iMore. To be honest I haven't updated using iTunes in a long time. The OTA worked fine for me. Hopefully someone will respond and help you with your issue. Enjoy and welcome.