final public static function checkFrameworkBuildVersion()
    {
        $f = json_decode(file_get_contents(__DIR__."/../../elements/config_files/core/framework.config.json"));

        if (!property_exists($f, 'installation')) {
            return (json_encode(array("code" => 500, "results" => "NOK", "fv" => "unknow",
                "msg" => "Property [installation] is undefined in framework.config.json file")));
        }

        if ($f->installation != null) {
            return (json_encode(array("code" => 500, "results" => "NOK", "fv" => "unknow",
                "msg" => "Cannot use iumio installer because you have already one app installed.")));
        }

        $v = $f->edition_version;
        $build = $f->edition_build;
        $e = $f->edition_fullname;
        $st = $f->edition_stage;

        if ($build >= self::$framework_build_accept) {
            $_SESSION['version'] = trim($v);
            return (json_encode(array("code" => 200, "results" => "OK", "fv" => trim($v), "edition" => $e,
                'stage' => $st)));
        } else {
            return (json_encode(array("code" => 500, "results" => "NOK", "fv" => trim($v),
                "msg" => "The version of iumio Framework is incompatible with iumio installer.
                 You must have at least version " . self::$framework_version_accept .
                    " of iumio Framework on your web server.")));
        }
    }