iTunes 12.10.10.2 has failed 3 times in a row to update iOS on iPhone 10s

The last three times (including just now) I've updated iOS on my iPhone 10s, iTunes on Windows 10 has refused to update my iPhone. The failure code is either 4000 or a complaint that my phone is locked (though it was unlocked when the update started). Updating to iOS 14 (14.0.1, 14.1 and just now, 14.2) has failed despite having the most recent version of iTunes.

On the 14.0.1 update, I switched to Wi-Fi and it worked. On 14.1, I kept trying, including setting autolock to NEVER, but after 4 attempts (and I rebooted my computer and phone between tries), not only would iTunes not update my iPhone, the Download and Update option under General/Software Update was greyed out. I had to put the phone into Recovery Mode to load 14.1 (restoring everything, including photos and music, took a looong time).

About 10 minutes ago, I unlocked my phone, set autolock to NEVER, and tried to update to 14.2. Got that same error dialog -- cannot update this iPhone. I rushed to switch to Wi-Fi update (did not want to go through Recovery mode again), and my phone is downloading the update as I type this (sadly, in my haste I did not record the precise error code from iTunes).

Anybody else having these problems? I am running Windows 10 x64 v2004 (build 19041.572) with all current patches, and as noted, iTunes 12.10.10.2.