Oracle Error Message
ORA-30751: cannot disable column string from storing objects of type string.string
Reason for the Error
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
Solution
Fix the cause of the error and retry the operation.