Fatal error: Uncaught RuntimeException: A middleware must be an object/class name referencing an implementation of MiddlewareInterface or a callable with a matching signature. in /var/www/html/vendor/slim/slim/Slim/MiddlewareDispatcher.php:100 Stack trace: #0 /var/www/html/vendor/slim/slim/Slim/Routing/Route.php(277): Slim\MiddlewareDispatcher->add(NULL) #1 /var/www/html/_includes/eventi.php(29): Slim\Routing\Route->add(NULL) #2 /var/www/html/vendor/slim/slim/Slim/Routing/RouteGroup.php(67): {closure:/var/www/html/_includes/eventi.php:16}(Object(Slim\Routing\RouteCollectorProxy)) #3 /var/www/html/vendor/slim/slim/Slim/Routing/RouteCollector.php(236): Slim\Routing\RouteGroup->collectRoutes() #4 /var/www/html/vendor/slim/slim/Slim/Routing/RouteCollectorProxy.php(179): Slim\Routing\RouteCollector->group('/eventi', Object(Closure)) #5 /var/www/html/_includes/eventi.php(16): Slim\Routing\RouteCollectorProxy->group('/eventi', Object(Closure)) #6 /var/www/html/index.php(82): require_once('/var/www/html/_...') #7 {main} thrown in /var/www/html/vendor/slim/slim/Slim/MiddlewareDispatcher.php on line 100