Being human being we have a lot of unlimited qualities. Listening is one of them. Normally we ignore it but it is most important for all. Good listing keeps us away from 99% problems away and life makes us simple but if we don’t listen properly we invite unlimited problem in our life. In same manner Listener in Oracle RDMS is much important. BEing DBA if we are not able to make a connection with Database we are unable to avoid problems. In this post, we are going to have look hoe we can solve “ORA-12505: TNS: listener does not currently know of SID given in connect descriptor”

Let’s have look on steps.

Cause: ORA-12505: TNS: listener does not currently know of SID given in connect descriptor

There are many possible causes for ORA-12505 but most common scenarios are:

The erroneous configuration in Server Side. Check the instances are known by the listener

lsnrctl services <listener name>

If the service is missing then add the service or correct it if it is incorrectly configured.
Stop the listener

# lsnrctl stop

Start the listener

#lsnrctl start

Let’s Check for an event in the listener.log file
Let’s Check Listener by pinging. Tnsnames.ora file contains the “net service name”. This file is used to identify server destinations. This file contains service name and database addresses. Count parameter is optional here, this parameter specifies the number of time it should try to connect.

# tnsping <net service name> <count>

Erroneous Configuration in Client Side. Fix the service name in tnsnames.ora file
Check listener by pinging

# tnsping <net service name> <count>

Today’s thought

Learn from the mistakes of others. You can’t live long enough to make them all yourselves. —Chanakya

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