Checked with the DB and the listener and db are up and able to connect to the db. But the application is not connecting to the db?
The listener is up , the message is from the listener indicating the listener does not know of SID/SERVICE name that you are giving it. Manually connect to the db using sqldeveloper in order to make sure the parameters you are providing are working. Pay special attention to SID vs SERVICE_NAME. Then try to open config tool and go back to your database connection info. Reconfigure your database connection. It will likely you will find your connection error there. Also sometimes the config tool has trouble figuring out whether you mean SID or SERVICE_NAME. You can open advanced properties on the connection in configtool and specify / or : in the url.
Thanks for the reply.