Not found
 The requested URL /apex/f was not found on this server

exec dbms_epg.set_dad_attribute('APEX', 'error-style', 'DebugStyle');

ORA-04031: unable to allocate 1292 bytes of shared memory ("large pool","unknown object","session heap","koh-kghu session heap")

Error in PLSQL code raised during plug-in processing.

404 - Not found 
The requested URL /apex/f was not found on this server

exec dbms_epg.delete_dad_attribute('APEX', 'error-style');

$ORACLE_BASE/admin/XE/bdump/xe_s00?_????.trc

/* Log levels:
0 - LOG_EMERG
1 - LOG_ALERT
2 - LOG_CRIT
3 - LOG_ERR
4 - LOG_WARNING
5 - LOG_NOTICE
6 - LOG_INFO
7 - LOG_DEBUG
*/
exec dbms_epg.set_global_attribute('log-level', '3');
exec dbms_epg.set_dad_attribute('APEX', 'error-style', 'DebugStyle');

select name, value from v$parameter where name like '%shared%serv%';

-- drop table dropme_session;
-- drop table dropme_lock;
-- drop table dropme_sql;

create table dropme_session as select * from v$session where 1 = 0;
create table dropme_lock as select * from v$lock where 1 = 0;
create table dropme_sql as select * from v$sql where 1 = 0;

-- Как зависло -- заполняем таблицы
insert into dropme_session
select * from v$session where client_identifier = :P_APP_USER || ':' || :P_SESSION; -- пользователь приложения и сессия APEX

insert into dropme_lock 
select * from v$lock where sid = (select sid from dropme_session);

insert into dropme_sql
select * from v$sql where address = (select sql_address from dropme_session);

commit;

-- И разбираемся.