itunes "cannot read the contents" of any i-device

Just a few days ago, I connected my iPhone, then my iPad, to my Mac, and received the error...

iTunes 12.9.5.5.

First, iOS 12.2, now 12.3.1, hoping that would fix things - it did not!

I do not think I am alone to this error, based upon recent internet search, but it is frustrating that I cannot access my devices!

Yesterday, all was fine loading offline videos onto my iPad, but today, I cannot!

Please help!