Error message

• Notice: Undefined variable: _SESSION in nplus_pn_filesystem_up() (linea 1170 di /var/www/drupal7_php56fpm/innolabs/drupal/sites/all/modules/nplus/nplus_pn/nplus_pn.module).
• Notice: Undefined index: current_parent_folder_id in nplus_pn_filesystem_up() (linea 1171 di /var/www/drupal7_php56fpm/innolabs/drupal/sites/all/modules/nplus/nplus_pn/nplus_pn.module).
• Notice: Array to string conversion in nplus_pn_filesystem_browse() (linea 1803 di /var/www/drupal7_php56fpm/innolabs/drupal/sites/all/modules/nplus/nplus_pn/nplus_pn.module).