Messaggio di errore

• Warning: Cannot modify header information - headers already sent by (output started at /web/htdocs/www.itsosplus.it/home/includes/common.inc:2791) in drupal_send_headers() (linea 1499 di /web/htdocs/www.itsosplus.it/home/includes/bootstrap.inc).
• Error: Class 'Drupal\form_builder\FormBase' not found in form_builder_cron() (linea 431 di /web/htdocs/www.itsosplus.it/home/sites/all/modules/form_builder/form_builder.module).