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Re: JDBC client causes TNS-12502 on server's listener

From: C. Ferguson <>
Date: Thu, 18 Jul 2002 16:15:39 -0700
Message-ID: <>


   here's my logic ;-) TNS-12502. Error message specifically for the TNSNAMES.ORA file. You say you are using the thin driver. It does not reference the tnsnames.ora file when making a connection. (yes, you already know that ;-) ) This eliminates your 2 apps as the problem.

   You say you see the log entries for the successful(?) attempts by your 2 apps that are checking connection states. And then you are seeing the TNS error messages between times. What else is attempting to make a connection to the database? Or asked differently, what else is trying to make a connection that would be referencing the tnsnames.ora file? (something besides your 2 apps, and probably an ODBC client).

   If it is easier, do as the docs say and ensure that the tnsnames.ora file is correct for whatever client is attempting to make the connection.

   hth and good hunting!

Enkidu Utnapishtim wrote:

> Cindy,
> Thanks for the quick reply Cindy. I checked with the developers and they 
> assure me that they're using Oracle's thin driver.
> We have just two main Java aps: our WebLogic app that checks connections 
> every 5 mintues (in case database loses a connection) and a "check" app 
> that attempts to connect every 10 minutes (verifies URL is accessible). 
> I can see entries for both of these in the log. But between are all the 
> TNS-12502 errors.
> Roger
> C. Ferguson wrote:

>> Well,
>> what driver are you using to connect to the oracle db? Try using
>> Oracle's thin driver (type4). See if that makes a difference.
>> hth,
>> Cindy
>> Enkidu Utnapishtim wrote:
>>> I am trying to research why a JDBC client (WebLogic java app) keeps
>>> generating a "TNS-12502: TNS:listener received no CONNECT_DATA from
>>> client" in my server's listener.log file. The message appears every
>>> minute or so (making my listener.log grow way too fast).
>>> I checked MetaLink and did a Google search (web and newsgroups).
>>> Practically every response says to check the tnsnames.ora on the
>>> client for a valid CONNECT_DATA entry. Well now, that's mighty fine
>>> advice if the client is anything other than a JDBC (or ODBC)
>>> connection. As far as I can determine, JDBC completely and totally
>>> ignores tnsnames.ora anyhow. That's why you have to put connect
>>> strings like "host:port:sid" in many of Oracle's Java wizards (eg,
>>> Portal Config Assistant) instead of the alias name from tnsnames.ora
>>> ... so it can construct a JDBC compliant connect string.
>>> So, my question is, where do I look (if not in the client's
>>> tnsnames.ora) for the problem?
>>> Thanks,
>>> Roger Crowley - LearningFramework - DBA

> Received on Thu Jul 18 2002 - 18:15:39 CDT

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