Error:
ORA-28040: No matching authentication protocol
Cause:
1. This problem was encountered on database instance version 12.2 and above and clients with version 9g/10g/11g.
Example: In my case the development team person was using 9g client
2. This error indicates a compatibility problem between the authentication protocol used on the client side and the server side.
3. The authentication protocol used on the server side depends on the SQLNET.ALLOWED_LOGON_VERSION_SERVER parameter in the sqlnet.ora file.
Workaround:
Upgrade to an Oracle client version that is compatible with the default value of the SQLNET.ALLOWED_LOGON_VERSION_SERVER parameter.
Ref from MOS https://support.oracle.com/epmos/faces/DocumentDisplay?parent=DOCUMENT&sourceId=2111118.1&id=207303.1
