ORA-00600: internal error code, arguments: [kzsviver:1], [], [], [], [], [],

in Oracle 11g

ORA-00600: internal error code, arguments: [kzsviver:1], [], [], [], [], [],

alter user xyz identified by values is null in pl sql block <<<<<<<<

example .....

my_text :=
'Alter user '
|| pwd.username
|| ' identified by values '
|| ''''
|| l_old_password
|| '''';
-- dbms_output.put_line(my_text);
EXECUTE IMMEDIATE (my_text);