error ORA-04088,ORA-01403,ORA-06512 on trigger restrict user after logon

Dear all,

I have a trigger to restrict user after logon database as below :

CREATE OR REPLACE TRIGGER SYS.test_AccessAFTER LOGON ON DATABASEDECLARE

v_osuser sys.v_$session.program%TYPE;v_program sys.v_$session.program%TYPE;v_module sys.v_$session.program%TYPE;v_username sys.v_$session.program%TYPE;BEGIN

SELECT osuser,program,module,username INTO v_osuser,v_program,v_module,v_username FROM sys.v_$sessionWHERE audsid = USERENV('SESSIONID')

AND audsid != 0 -- Don't Check SYS ConnectionsAND ROWNUM = 1; -- Parallel processes will have the same AUDSID'sif (upper(v_program) like 'TOAD%'