Connecting to Oracle19C Server using Oracle11g client

all

I'm trying to connect to an Oracle 19C database. I have installed two Oracle Clients (11g and 12c) because we need to support legacy programs. I can connect with no issue with any user using sqlplus through the 12c client. But if I use the 11g (11.2.0) client with any user. I always get:

ERROR:
ORA-01017: invalid username/password; logon denied

Both clients have exactly the same sqlnet.ora and tnsnames.ora files, so both clients point to the same database.

Any idea? Do I need to set some specific configuration in the 19c server? Or do I need to make some change in the 11g client? Is this even possible?

Thank you.

Have a look at Client / Server Interoperability Support Matrix for Different Oracle Versions (Doc ID 207303.1)

• #9 - 11.2.0.3 or 11.2.0.4 only. For Oracle Autonomous Transaction Processing and Oracle Autonomous Data Warehouse, there is additional limitation and 11.2.0.4 is the minimum supported client version.

Usually it is a bad idea to install more than one Oracle client (i.e. one each for 32-bit and 64-bit).

For some components, e.g. "Oracle OleDB Provider" it is even not possible to have more than just one version (again, one each for 32-bit and 64-bit) installed. This is a limitation of the old Windows COM architecture.

For other components it may work, however you need to set your %PATH% environment variable accordingly that it points to the correct folder where currently desired version is installed.