How to return the native web interface to elastix?

Question

freepbx

Good afternoon!
After updating freepbx to elastix 2.5, the former replaced the elastix web interface.
Apparently, this is a bug in elasticix 2.5
after updating /var/www/html/index.php contained

<?php
if (file_exists(dirname(__FILE__) . '/index_custom.php')) {
          include_once(dirname(__FILE__) . '/index_custom.php');
} else {
          header('Location: /admin');
}

The correct index.php in the comment is questionable.