Solving the ORA-12504 Error

Oracle DB ORA-12504 error

When attempting to use the ODBC Data Source Administrator to test a connection to an Oracle Database from an Oracle client – one that did not have TNSPING installed – I got the above error:

Unable to connect
[Oracle][ODBC][Ora]ORA-12504: TNS:listener was not given the SERVICE_NAME in CONNECT_DATA

When searching this error, I found quite a few Stack Overflow articles. Unfortunately, none of them solved the problem.

I was able to apply the remedy to a different issue to this one, and fortunately it worked.

For whatever reason, this client, though not the Instant Client as was the case in the previous article, was missing the “.ora” configuration files and the TNS_ADMIN environment variable. Once these were created, the client worked as expected.