We have SQL Server 2014, with the latest CU, running with Oracle client version installed.

We have about 25 linked Oracle servers connected on it. The servers are running of mix of Oracle 10,11,12 and 19, and can connect to all without issues.

We're trying to connect this SQL server to 2 new Oracle servers (A Production, and BCV copy), which are both running 19.

While attempting to connect to the Prod server, we get the ORA-28040: No matching authentication protocol error.

enter image description here While attempting to connect to the BCV server, The username/password gets rejected.

  • It will connect fine to either server directly in Oracle SQL developer, therefore we're certain about the credentials and TNS entries

  • Can TNSPing both Oracle servers on the SQL server box just fine

  • I don't see how this can be a compatibility issue, as we've linked four Oracle 19 servers

  • The PASSWORD_VERSION attributes for the Oracle login is set to 11G 12C

  • We've added the 2 attributes in the SQLnet.ora file, but no luck:



Anything we're missing here?

1 Answer 1


Per the documentation, Oracle Database 19c requires a minimum client version of, so you will need to upgrade your client.

You will also need to reset the passwords for all users with this client after setting the PASSWORD_VERSION parameter to ensure that password hashes with the compatible 11G algorithms are generated.

  • Thanks! I successfully patched the client and can connect without issues. Didn't have to change passwords though. Commented Mar 24, 2023 at 17:10

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