ORA-28040: No matching authentication protocol

Question

I am facing this issue even after following the below settings.

1. Replacing ojdbc14.jar with ojdbc6.jar[also tried ojdbc5.jar]

2. Added "SQLNET.ALLOWED_LOGON_VERSION_SERVER=8" to sqlnet.ora file[under network/admin folder].

This is happening after upgrading the DB from 11g to 12c.

Answer 1

ORA-28040: No matching authentication protocol

I faced a similar issue when trying to connect a

32-bit Oracle 11g Client to a 64-bit Oracle 12c Server

I then proceeded to add the following to sqlnet.ora

SQLNET.ALLOWED_LOGON_VERSION_CLIENT = 8
SQLNET.ALLOWED_LOGON_VERSION_SERVER = 8

I then experienced the following error

ORA-01017: invalid username/password: logon denied

Adding the following to the Client sqlnet.ora as well as the Server, I was able to connect an old version of Toad and PL/SQL to the new 12c Server.

SQLNET.AUTHENTICATION_SERVICES = (NONE)

Answer 2

JDBC drivers have both a Java version and an Oracle version. The versions are usually correlated, but it's possible for an ojdbc14.jar to support a later version of Oracle than a ojdbc6.jar. Make sure you are using the latest version of ojdbc6.jar.

Run this command to see which version of Oracle the driver was built for:

>java -jar ojdbc6.jar -getversion
Oracle 11.2.0.3.0 JDBC 4.0 compiled with JDK6 on Thu_Jun_28_00:38:25_PDT_2012
#Default Connection Properties Resource
#Mon Dec 21 12:38:41 CST 2015

For SQLNET.ORA changes, to be safe you should restart both the listener and the database. This sounds extreme, but there are some parameters that require restarting the database.

Also make sure that you are modifying all relevant SQLNET.ORA files. If the database's Oracle home is different than the listener's Oracle home you should modify both.