Problema:

Erro de INVALID PASSWORD ao reconfigurar o EM no Oracle 10gR2.
oracle@capin:~$ emctl config emkey -repos -sysman_pwd ORACLE
TZ set to Brazil/East
Oracle Enterprise Manager 10g Database Control Release 10.2.0.4.0
Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.

Invalid Password
caught Exception java.sql.SQLException: 
Listener refused the connection with the following error: 
ORA-12514, TNS:listener does not currently know of service requested 
in connect descriptor 
The Connection descriptor used by the client was:
(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)
(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=TESTE_TNS)))

Dados adicionais:
Database UP;
Listener UP;
Ubuntu Server (para testes);
Database 10.2.0.4.0;

Obs.: Não é problema do Ubuntu, pois buscando no google vários SO com problemas parecidos.

Solução:

oracle@capin:~$ emctl config emkey -repos -sysman_pwd ORACLE
TZ set to Brazil/East
Oracle Enterprise Manager 10g Database Control Release 10.2.0.4.0
Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.

Invalid Password
caught Exception java.sql.SQLException: Listener refused the connection with the following error:
ORA-12514, TNS:listener does not currently know of service requested in connect descriptor
The Connection descriptor used by the client was:
(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521)))(CONNECT_DATA=(SERVICE_NAME=TESTE_TNS)))

oracle@capin:~$ sqlplus system@TESTE_TNS

SQL*Plus: Release 10.2.0.4.0 – Production on Sat Apr 21 18:20:54 2012

Copyright (c) 1982, 2007, Oracle. All Rights Reserved.

Enter password:
ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified

Não existia o TNSNAMES.ORA;

oracle@capin:~$ locate tnsnames
/opt/oracle/app/oracle/product/10.2/db_1/hs/admin/tnsnames.ora.sample
/opt/oracle/app/oracle/product/10.2/db_1/network/admin/samples/tnsnames.ora

oracle@capin:/opt/oracle/app/oracle/product/10.2/db_1/network/admin$ vim tnsnames.ora
TESTE_TNS =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 666))
)
(CONNECT_DATA =
(SID = TESTE_TNS)
)
)

oracle@capin:/opt/oracle/app/oracle/product/10.2/db_1/network/admin$ sqlplus system@TESTE_TNS

SQL*Plus: Release 10.2.0.4.0 – Production on Sat Apr 21 18:29:23 2012

Copyright (c) 1982, 2007, Oracle. All Rights Reserved.

Enter password:

Conectado a:
Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> exit

oracle@capin:~$ emctl config emkey -repos -sysman_pwd ORACLE
TZ set to Brazil/East
Oracle Enterprise Manager 10g Database Control Release 10.2.0.4.0
Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.

The Em Key has been configured successfully.

oracle@capin:~$ emctl secure dbconsole -sysman_pwd ORACLE
TZ set to Brazil/East
Oracle Enterprise Manager 10g Database Control Release 10.2.0.4.0
Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.
http://127.0.0.1:666/em/console/aboutApplication
DBCONSOLE already stopped… Done.
Agent is already stopped… Done.
Securing dbconsole… Started.
Checking Repository… Done.
Checking Em Key… Done.
Checking Repository for an existing Enterprise Manager Root Key… Done.
Generating Enterprise Manager Root Key (this takes a minute)…Failed to create Enterprise Manager Root Key. OUTRO ERRO:

REMOVENDO E ADICIONANDO REPOSITÓRIO:
Agora vou remover o repositório do EM e criar novamente, atençãos nas configurações.
emca -deconfig dbcontrol db -repos drop
emca -config dbcontrol db -repos create

Executado os procedimentos acima, mas acaba que agora vai:
oracle@capin:~$ emctl start dbconsole
TZ set to Brazil/East
Oracle Enterprise Manager 10g Database Control Release 10.2.0.4.0
Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.
https://127.0.0.1:666/em/console/aboutApplication
– An instance of Oracle Enterprise Manager 10g Database Control is already running.
oracle@capin:~$ emctl status dbconsole
TZ set to Brazil/East
Oracle Enterprise Manager 10g Database Control Release 10.2.0.4.0
Copyright (c) 1996, 2007 Oracle Corporation. All rights reserved.
https://127.0.0.1:666/em/console/aboutApplication
Oracle Enterprise Manager 10g is not running.
——————————————————————
Logs are generated in directory /opt/oracle/app/oracle/product/10.2/db_1/TESTE_XXX/sysman/log

Para solucionar isso foi reiniciado, isso que tentei dar um kill -9 no processo do emctl que estava rodando, mas enfim, o procedimento agora funcionou.

Att,
capin