PLS-00684
invalid data type for the JSON return value
Cause
A JSON function was specified with an unsupported return type. The following are supported as return types of each JSON function: -JSON_OBJECT, JSON_ARRAY: varchar2 -JSON_VALUE varchar2, raw, number, boolean, sdo_geometry, blob, clob date, timestamp, timestamp_with_time_zone -JSON_QUERY varchar2, raw, blob, clob
Action
Specify a supported data type as the JSON function return type.