Unable to connect to the database server

This either means that the connection credentials in your settings.php file are incorrect or the ORACLE database server cannot be reached.

The error message returned was: ORA-00257: archiver error. Connect internal only, until freed..

Currently, the username is LIBRERIA and the ORACLE instance is identified as mora.

For more help, see the Installation and upgrading handbook. If you are unsure what these terms mean you should probably contact your hosting provider.