ORA-12154 could not resolve the connect identifier specified

Question

I have switched over to the 64bit Windows 7 and created a simple web app to test the connection to the database. I am using VS 2010 - plain asp.net web project and I am runn

Answer 1

I am going to assume you are using the tnsnames.ora file to specify your available database services. If so connection errors usually come down to two things.

1. The application cannot find the TNS entry you specified in the connection string.

2. The TNS entry was found, but the IP or host is not correct in the tnsnames.ora file.

To expand on number 1 (which I think is your problem). When you tell Oracle to connect using something like:

sqlplus user/pass@service

The service is defined in the tnsnames.ora file. If I attempt to connect with a service that is not defined in my tnsnames.ora, I get the error you get:

[sodonnel@home ~]$ sqlplus sodonnel/sodonnel@nowhere

SQL*Plus: Release 11.2.0.1.0 Production on Mon Oct 31 21:42:15 2011

Copyright (c) 1982, 2009, Oracle.  All rights reserved.

ERROR:
ORA-12154: TNS:could not resolve the connect identifier specified

So you need to check a few things:

1. Is there a tnsnames.ora file - I think yes because your console can connect
2. Is there an entry in the file for the service - I think also yes as the console connects
3. Can the application find the tnsnames.ora?

Your problem may well be number 3 - does the application run as a different user than when you run the console?

Oracle looks for the tnsnames.ora file in the directory defined in the TNS_ADMIN environment variable - If you are running as different users, then maybe the TNS_ADMIN environment variable is not set, and therefore it cannot find the file?