Oracle Message OCI-21601 - attribute is not an object

ERRORattribute is not an object
CAUSEThe user attempts to perform an operation (that is valid only for an object) to an attribute of a built-in type. An example of such an illegal operation is to dynamically set a null structure to an attribute of a built-in type.
ACTIONUser should avoid performing such operation to an attribute of built-in type.