The Derived Persistent Type Is Part Of a Flat Inheritance Hierarchy But Contains Properties Mapped To Not-Nullable Columns
This error occurs when a derived persistent class is part of a flat inheritance hierarchy and contains properties mapped to not-nullable columns in the same time.
To resolve this error, set the 'allow nulls' attribute for all columns mapped to this class to True.
- Double-click the error to open the Validation Dialog.
Apply the automatic fix for setting the 'allow nulls' attribute.