"cannot disable column %s from storing objects of type %s.%s"
*Cause: The user is trying to drop a type from being stored in a
substitutable column or table. This error is raised due to one
of the following reasons :
- the column is enabled to store instances of some subtype of
the type being dropped.
- the column is enabled to store instances of only one type
*Action: Fix the cause of the error and retry the operation.