Please see Mittwoch about Site Identity and the menu set up. The error message indicates that there isn't a PHP Layers menu set properly. In this version of Tiki, the menu id number must be part of the Site Identity custom code.
(In Tiki 1.10, the customization/personalization will be quite a bit simpler. Because that version enables setting the menu id number as a config option, there's no need for the custom code.)