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I'm using Oracle 11gR2 in RHEL5. Now a days my application, during run time, is showing exception as below.

  Listener refused the connection with the following error:
ORA-12519, TNS:no appropriate service handler found


 Listener refused the connection with the following error:
ORA-12505, TNS:listener does not currently know of SID given in connect descriptor

It happens only during the peak time.

Where can I find the reason? Somewhere it might be logging all. Where is it? I checked the alert_db.log as well as log.xml inside the tnslsnr, but couldn't find anything relating this.

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The documentation explains how to go about configuring listener tracing, but in summary:



You can up the TRACE_LEVEL to admin or support if you need more information, but be aware that they generate increasing amounts of output.

Your issue could be due to either a DB not being able to service a request due to the maximum number of processes being reached (check the alert log), a lack of resources on the box (are kernel parameters set correctly?) or an outright DB crash.

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In the alert log I didn't found anything relating to this. – Maximin Nov 22 '13 at 11:58

Is the database running? Execute:

ps -ef | grep pmon.

You can re-register the database with the listener by executing the statement:


If you execute it, you should is a log message in listener.log immediately. But under normal circumstances the database does this by it's own periodically. You can also check database parameters listener, local_listener, ... Or you can use old style way, you can "hardcode" the database's SID directly in listener.ora.

PS: what the the load of the system?

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