The exception is fixed. To evaluate the IsReadOnlyBinding of the column, we do not use the built-in binding mechanism but a custom one. This custom binding mechanism is designed to use as a source only the default one which is the current item of the ItemsSource of RadGridView. This is the reason that the scenario where the default source of the binding is changed is not supported by design. 

Available in LIB version 2017.1.213 , it will be also available in the R1 2017 SP1 Release.