[SOLVED]Error in 8.5.7 Whoops \ Exception \ ErrorException (E_ERROR)

i have the following error, have you some tip?

Whoops \ Exception \ ErrorException (E_ERROR)
Call to a member function getThumbnail() on null

 Whoops\Exception\ErrorException
/var/www/vhosts/fondazionecologni.it/httpdocs/application/themes/gbnt/interview.php10
1
Whoops\Run handleError
…/vendor/filp/whoops/src/Whoops/Run.php487
0
Whoops\Run handleShutdown
[internal]0

You have probably to check if given object exists before using getThumbnail()

if (is_object($xxx) {
    $xxx->getThumbnail();
}

or load thumbnail helper

$app = \Concrete\Core\Support\Facade\Application::getFacadeApplication();
$ih = $app->make('helper/image');
$thumbnail = $ih->getThumbnail($fileObject, $width, $height, $crop)

depending which getThumbnail() method it is.

ok, thanks, i found many configurations in the server to fix and after i managed to upgrade successfully

Enrico