I discovery the error.
in the file /wp-admin/index.php, in the line 128 is necessary correct the name of the function “right_now”. The correct form is: <?php update_rightnow_message(); ?>
in the file /wp-admin/includes/update.php, is necessary do the same in the line 46. The correct line is: function update_rightnow_message() {
With me resolve the problem.
See you.