If you ever tried to start the Enterprise Manager with the command ‘emctl start dbconsole’ and you got stuck with the error:

OC4J Configuration issue. <ORACLE_HOME>/oc4j/j2ee/OC4J_DBConsole_<YOURHOST>_<YOURDB> not found.

.

for instance:

OC4J Configuration issue. /opt/oracle/product/10.2.0/db_1/oc4j/j2ee/OC4J_DBConsole_db.neoface.pt_ORCL not found.
.

Then the cause may be that Database Control is not configured or misconfigured… This can be verified by checking if the following directories exist in your ORACLE_HOME:

<ORACLE_HOME>/oc4j/j2ee/OC4J_DBConsole_<HOSTNAME>_<DBNAME>
<ORACLE_HOME>/<HOSTNAME>_<DBNAME>
.

If those directories do not exist, Database Control has not been configured for the database.

SOLUTION

To configure the enterprise manager database control for your database, issue the following commands as oracle user:

[oracle@neoface oracle]$ export ORACLE_HOME=<ORACLE_HOME>
[oracle@neoface oracle]$ export ORACLE_SID=<ORACLE_SID>
[oracle@neoface bin]$ cd $ORACLE_HOME/bin
[oracle@neoface bin]$ ./emca -config dbcontrol db -repos create

Now just follow the instructions on the screen… you’ll need the SYS, DBSNMP and SYSAUX passwords.

Sometimes you already have the SYSMAN, DBSNMP and SYSAUX accounts, and the previous EMCA command can fail to create the DBConsole repository the error ORA-20001 occurs.

ORA-20001 Sysman Already Exists While Running EMCA
.

The Solution is simple… Drop the existing repository

[oracle@neoface oracle]$ cd $ORACLE_HOME/bin
[oracle@neoface bin]$ ./emca -deconfig dbcontrol db -repos drop

After removing the repository try to created it with the commands I explained previously. After you install the EM repositiry, the DBConsole should be started and you should be able to access the DBConsole using the URL provided at the installation screen.

(UPDATE)

If the previous drop procedure fails and by checking the logs we see an ORA-01031 insufficient privileges, this may be because we don’t have a password file created. Just go to $ORACLE_HOME/dbs and check if we have a file called pwd<sid>.ora. If not, create it…

[oracle@neoface oracle]$ cd $ORACLE_HOME/bin
[oracle@neoface bin]$ ./orapwd file=$ORACLE_HOME/dbs/pwd<sid>.ora password=oracle entries=5

Hope it helps!