ORA-ERROR which every DBA facing

ORA- 12514,ORA-12537,ORA-00600/ORA-07445,  ORA-12154

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.
– 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.


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




* 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.
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.
* You can disable these parameters in the Sqlnet.ora
* Or add the client machines ip address in the TCP.INVITEDNODES list.
Clause: Most likely it is related to bug
Solution: go to metalink and apply patch set.


Clause:Mis-configuration of SGA, insufficient memory
Solution: Sametime need to add memory on system, or sametime need to reduce SGA memory
Clause: Wrong TNS_ENTRY is used.
Solution: Using NETCA tools configure tns entry or check tnsnames.ora file for correct entry.
Clause: It is generic error lots of reason


Clause: It is generic error lots of reason
Solution: increase “processes” parameter, increase physical memory


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)

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