App Store notifies that iTunes 12.5.1 is available. But when I try to update it, I get:
“iTunes” could not be verified.(311)
The error is issued when download completes and App Store is verying something. I'm suspicious that it may be related to my GM Sierra install since it is not strictly 'offically final'.
BTW, I also get strange errors when updating Adobe Flash yesterday. I remember I got something "no permission to install".