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Don Burleson Blog 







TNS-12514 on Windows

Expert Oracle Database Tips by Donald BurlesonMarch 30, 2015


Question:  My database was running fine and all of a sudden I am getting the TNS-12514 error:

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

I am running on Windows. 

I now get the TNS-12514 constantly, and I did not change my listener.ora or tnsnames.ora files.  

Is this TNS-12514 error a Windows problem?

Answer:  Your ROOT CAUSE is that you are running on Windows!  

BEWARE: Windows IS NOT robust enough for any mission critical system, especially with the Windows virus issues and weekly patches.

My Windows systems crash at a rate at LEAST 4 times more often than Linux/UNIX.

To diagnose the TNS-12514 error, see these diagnostics for the TNS-12514 error.  

Diagnosing the TNS-12514 in Windows

 In Windows when, for unknown reasons, Oracle is refusing connections, I have seen Windows TNS-12514 problems with any of these issues:

  •  A Windows screen saver causes CPU hogging that makes connections get refused

  • Somebody installed a Windows virus scanner

  • A weekly Windows patch application has caused a problem

  • Never apply a Windows patch unless it is to address a known Oracle problem

  • You have a Windows virus.  For example, the Nimbda virus can cause a TNS-12514.

FIRST THING, I would bounce ALL of your Windows services (or just bounce the whole PC Windows server):

Then, verify that all of your Windows services are running properly.

If you continue to get the TNS-12514 error, follow these Oracle TNS networking diagnostic steps

The oerr utility shows this for the ORA-12514 and TNS-12514 error:

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

  •  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.

Burleson Forum user and Oracle expert, Dave, notes:

It appears in a TNS-12514 error that your database isn't registering itself with the listener.

Issue an alter system register xxx and lsnrctl status from SQL*Plus and see if the listener knows about your database  

Then issue a show parameter local_listener to show what the database thinks about the listener status.

Failing that, place a static entry in the listener.ora for the database service name and the TNS-12514 may be fixed.  

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