ORA-ERROR which every DBA facing

ORA- 12514: TNS:listener does not currently know of service requested in connect descriptor.

        

Cause:- The listener received a request to establish a connection to a database or other service. The connect descriptor received by the listener specified a service name for a service (usually a database service) that either has not yet dynamically registered with the listener or has not been statically configured for the listener. This may be a temporary condition such as after the listener has started, but before the database instance has registered with the listener.

          

 Action:

- Wait a moment and try to connect a second time.

- Check which services are currently known by the listener by executing: lsnrctl services <listener name>

- Check that the SERVICE_NAME parameter in the connect descriptor of the net service name used specifies a service known by the listener.

- If an easy connect naming connect identifier was used, check that the service name specified is a service known by the listener.

- Check for an event in the listener.log file.

   ORA-12537: TNS: connection closed error

Question:  I'm trying to connect to Oracle and I get the ORA-12537: TNS: connection closed error.  How do I fix an ORA-12537?

Answer: The ORA-12537 is an informational error, and the "real" error is the secondary error message.

Error:- 

Tnsping Net Service Name fails with TNS-12537: TNS:connection closed or Sqlplus connection errors out with Ora-12537

Cause:

* In the Sqlnet.ora file the parameter TCP.VALIDNODE_CHECKING is enabled and TCP.INVITEDNODES is set to some specific IP's of the Client Machine.

Error:-

If trying to connect to the Apps database, by default, with Oracle Apps Installation the parameter TCP.VALIDNODE_CHECKING is enabled and TCP.INVITEDNODES is set to Server Machines IP or Hostname.

Solution

* You can disable these parameters in the Sqlnet.ora

* Or add the client machines ip address in the TCP.INVITEDNODES list.

ORA-00600/ORA-07445

Clause: Most likely it is related to bug

Solution: go to metalink and apply patch set.

ORA-04031

Clause: Mis-configuration of SGA, insufficient memory

Solution: Sametime need to add memory on system, or sametime need to reduce SGA memory

  ORA-12154

Clause: Wrong TNS_ENTRY is used.

Solution: Using NETCA tools configure tns entry or check tnsnames.ora file for correct entry.

  ORA-12368

Clause: It is generic error lots of reason

Solution: Edit SQLNET.ORA and change NONE from NTS "SQLNET.AUTHENTICATION_SERVICES=NONE"

ORA-12500

Clause: It is generic error lots of reason

Solution: increase "processes" parameter, increase physical memory

ORA-12528

Clause: It is BUG in 10g (if you face this error in 10g)

Solution: Don't use TNS_ENTRY with connect string or edit listener configuration from STATIC to DYNAMIC.(search on my blog for more)