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;
Forcing an ORA-40478 error with the error clause for json_table: 
select * from
   json_table ('[
     [1, "one"  , "B"],
     [2, "two"  , "C"],
     [3, "three", "D"],
     [4, "four" , "E"],
    ]',
   '$[*]'
    ERROR ON ERROR
    columns
       id    number  ( 1) path '$[0]' ,
       num   varchar2( 4) path '$[1]' ,
       meta  varchar2( 3) path '$[2]'
    );
--
-- ORA-40478: output value too large (maximum: 4)
--

See also

Other Oracle error messages

Index

Fatal error: Uncaught PDOException: SQLSTATE[HY000]: General error: 8 attempt to write a readonly database in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php:78 Stack trace: #0 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(78): PDOStatement->execute(Array) #1 /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php(30): insert_webrequest_('/notes/developm...', 1758207385, '216.73.216.150', 'Mozilla/5.0 App...', NULL) #2 /home/httpd/vhosts/renenyffenegger.ch/httpsdocs/notes/development/databases/Oracle/errors/ORA-40478_output-value-too-large_maximum(87): insert_webrequest() #3 {main} thrown in /home/httpd/vhosts/renenyffenegger.ch/php/web-request-database.php on line 78