Resolution
In Oracle Database 12c parameter Allowed_Logon_Version is deprecated in SQLNet.ora
This parameter is been replaced by 2 new parameters
SQLNET.Allowed_Logon_Version_Server
SQLNET.Allowed_Logon_Version_Client
In Oracle Database 12c parameter Allowed_Logon_Version is deprecated in SQLNet.ora
This parameter is been replaced by 2 new parameters
SQLNET.Allowed_Logon_Version_Server
SQLNET.Allowed_Logon_Version_Client