i am new to oracle.last two days i cant able to open OEM.when i atttempt it says the error
Listener refused the connection with the following error: ORA-12505, TNS:listener does not currently know of SID given in connect descriptor The Connection descriptor used by the client was: (description=(address=(host=localhost)(protocol=tcp)(port=1521))(connect_data=(sid=orcl)(server=dedicated)))
Current Status - OPEN
but i dont know even what is listener and where the file located and how to resolve it.
Listener is a components that allows remote connections to be established with the database. If this component is down, neither EM nor any other program can access the database remotely. Seems like in your case the database is not registered with the listener and depending on the database version, it may require changes to the listener config file (listerner.ora). I suggest you file a service request with Support and they can guide you with this process step-by-step.