Installation Guide for Oracle Fusion Middleware 11g Run the Repository Creation Utility Troubleshooting the RCU Troubleshooting the RCU If the RCU fails to connect to the Oracle database, follow the steps below. Stop the listener. /app/oracle/product/11.2.0/db_home1/bin/lsnrctl stop LISTENER As root, edit the /etc/hosts file and remove your <server name> in the 127.0.0.1 and ::1 line. 127.0.0.1 localhost.localdomain localhost.localdomain localhost4 localhost4.localdomain4 localhost centosTemplate <server_name> ::1 localhost.localdomain localhost.localdomain localhost6 localhost6.localdomain6 localhost centosTemplate <server_name> Restart the listener. /app/oracle/product/11.2.0/db_home1/bin/lsnrctl start LISTENER Double check the status. /app/oracle/product/11.2.0/db_home1/bin/lsnrctl status LISTENER Look for the server name after the HOST parameter. Listening Endpoints Summary... (DESCRIPTION=(ADDRESS=(PROTOCOL=ipc)(KEY=EXTPROC1521))) (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=<server_name>)(PORT=1521))) Try to connect to the Oracle database again.