Why does AdornedElement.(Validation.Errors).CurrentItem.ErrorContent now (VS2017 15.4) cause intellisense errors?

Question

I\'ve been using the following error adorner template for a long time now:

Answer 1

The ReadOnlyObservableCollection itself doesn't expose a CurrentItem property. Instead, the CurrentItem is a concept of the CollectionView that is internally created when a collection of items is bound in WPF.

There is some special support to access the CurrentItem of a collection by using / in the binding path.

Change the binding path to Path=AdornedElement.(Validation.Errors)/ErrorContent to utilize this support.