Hi Pols12 and thank for your help
i've turn to development mode and now i can see the error
Fatal error: Call to a member function getMessage() on null in /var/www/html/omeka-s-beta4/application/view/error/index.phtml on line 6
i dont't understand
in my instance omeka-s i've no Zend directory in application/librairies and all sites works fine
in omeka-s-beta4 instance the same (no Zend directory) but i can't use "view" for all sites
many a problem with modules...