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11g: Persistent TNS-12537/ORA-609 Errors & LSNRCTL Hangs (Doc ID 1532481.1)

Last updated on MARCH 31, 2022

Applies to:

Oracle Net Services - Version to [Release 11.1 to 11.2]
Information in this document applies to any platform.
This problem / solution is relevant only to - The problem is resolved in We are describing a situation where all incoming remote connections are failing with a variety of errors. At the same time, the LSNRCTL utility is failing to return a "status" or "services" result in a timely manner.


There are numerous symptoms that can arise with this issue.

1)  The LSNRCTL utility is slow to respond or seems to hang indefinitely.

2)  Remote client connections are slow to respond or timeout.

3)  There are  frequently repeating ORA-609 errors in the alert.log while this problem is occurring

4)  The listener log might show the following errors being thrown repeatedly as client connections are failing:




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