Search notes:

ORA-40478: output value too large (maximum: N)

The following statement is likely to throw an ORA-40478 error:

select
   owner,
   json_arrayagg(json_array(
      obj.object_name,
      obj.object_type,
      obj.created
   ))
from
   dba_objects obj
where
   obj.owner not in ('SYS', 'SYSTEM')
group by
   owner;

Use the returning clob clause for the json_arrayagg function to prevent the ORA-40478 error:

select
   owner,
   json_arrayagg(json_array(
      obj.object_name,
      obj.object_type,
      obj.created
   )
   RETURNING CLOB
   )
from
   dba_objects obj
where
   obj.owner not in ('SYS', 'SYSTEM')
group by
   owner;

ORA-40478: output value too large (maximum: N)

See also