I'm not even trying to sync apps. I only want to sync one movie. When I try to sync, I get this error message.
I click the Authorize button, it asks me to enter my iTunes password, and after that, it gives me this error.
I even tried to go to the menu > iTunes Store > Authorize This Computer, but it still gives the error. I also tried to de-authorize the computer, but it gives the same error when I try to authorize. I ran the diagnostics in iTunes and they all passed. (I did not run the CD test.) I checked for updates and it says it is the latest. I have the box checked in preferences to "Automatically Update".
Windows 8.1, iPhone 5, iOS 9.2.1, iTunes 18.104.22.168