Trusting my computer with my iPhone no longer unlocks it for access (iPhone 5 w/iOS10, and Mac OSX 10.7.5)
It appears the contents of

/var/db/lockdown


a folder on your mac, are corrupt.

First, unplug your iPhone or iPad.

Quit any apps that try to communicate with the iDevice e.g. Photos, Image Capture, iTunes, PhoneView, iMazing, iFunbox or Dropbox.

Delete the files within /var/db/lockdown/ (not the folder).

Plug your iDevice back in.

The “Trust this computer?” dialog box should appear. Tap Trust on your iDevice.

The operating system should create new .plist files in the lockdown folder. Try reopening one of the apps that had the error.