Example :
SQL> alter user u1 identified by u1
2 /
alter user u1 identified by u1
*
ERROR at line 1:
ORA-00604: error occurred at recursive SQL level 1
ORA-06502: PL/SQL: numeric or value error: character string buffer too small
ORA-06512: at line 6
Solution :
SQL> alter system set "_system_trig_enabled"=FALSE;
System altered.
Enjoy
Osama Mustafa