I want to edit an existing for created with quform. Whene trying to save, I get the message: “Fehler: das Formular konnte nicht gespeichert werden.” (Error, the form could not be saved). Thies does not happen when creating ans saving a new form. The PHP error log shows the entry: 2016-04-26 10:44:05 195.160.xxx.xx:64350 AH01215: Failed loading /usr/local/lib/ZendOptimizer.so: /usr/local/lib/ZendOptimizer.so: undefined symbol: empty_string, referer https://www.MyDomain.de/wp-admin/admin.php?page=iphorm_form_builder&id=3 The frontend seems to be working fine.