I support an IIS 7.5 web server and I've been having a bit of trouble with my app pools. What I am seeing is every so often, the applications using connections to Oracle databases will stop working and throw a "ORA-12154: TNS:could not resolve the connect identifier specified" error. What's maddening is that nothing has changed on the db server, web server, or inside the app. I've tried a TNS Ping to the database and it connects just fine. Apps in the same app pool using SQL Server databases don't seem to have an issue.

IMPORTANT: If I change the app to belong to a different app pool, it starts working again. If I change it back to the original app pool, the error persists.

What could be happening here? I'm at a loss as to why the issue would just pop up out of the blue and only affect certain pools.


  • EDIT: This also happens on applications using SQL Server 2008, so it appears it is not just Oracle to blame. – pburgh Mar 13 '15 at 11:33

Try pinging your TNS listener to see if it's up something like this on Linux:

tnsping oracle
Used TNSNAMES adapter to resolve the alias
Attempting to contact (DESCRIPTION = (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521)) (CONNECT_DATA = (SERVER = DEDICATED) (SERVICE_NAME = oracle)))
OK (2311770 msec)

If its up but you can't get status from TNS listener like this:

lsnrctl status
TNS-01153: Failed to process string: �9M0

Try forcing the listener to refresh without errors with the following command (again this is linux look for equivalent Windows Server command):

lsnrctl start oracle
TNS-01106: Listener using listener name LISTENER has already been started

It might be related with hardware/and/or/bad oracle tunning/and/or/bad oracle's configuration i have exactly the same error than you except i'm running Apache-Tomcat as a webserver, and right away after i start the webserver my oracle service stops (TNS:listener error, and on my webapp i see the Socket Time Out exception) it's not like you having the chance of actually running your apps for a while before the TNS service stops, i guess that's the OS part.

I'm using a Virtual Machine, VM Fusion with CentOS 6.6 installed, this VM runs just fine on only 1 of 3 different laptops, i can confirm it could be related with RAM memory, how does it looks your server's RAM when that happens ? i incremented this several times and it fixed the issue but then came back ant the only way to get rid of it was to monitor RAM and auto-clean it when reaches maximum then forcing it to run with:

lsnrctl start oracle
  • Welcome to Server Fault! Your answer currently does not seem to provide a workable solution to the question and might be more appropriate as a comment. Please read How do I write a good answer? and consider revising or deleting your current answer. – Paul Mar 10 '15 at 21:31
  • I added info above... I recently found that it's not just Oracle apps that are falling over. Apps using SQL Server also stop working. – pburgh Mar 13 '15 at 11:34

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