TYPO3 Core

Forming and ajax widget uri, makes a call to the page type 7076 defined in fluidAjaxWidgetResponse. This page uses a USER object with an userfunc to TYPO3\CMS\Fluid\Core\Widget\Bootstrap->run.

This function is a wrapper of the extbase bootstrap function \TYPO3\CMS\Extbase\Core\Bootstrap and works correctly except when the fluid widget view helper is not part of o plugin.

But this can be a usual scenario when, for instance, you call the viewhelper from a configuration extension of a project.