this issue is related to admin created user access. it is occurs if user try to access unauthorised resources
i suggest you to do the following  two things

1) check your acl.xml file and provide access to the resource from backend using administrator credencials navigate to system>>user roles>>resources and checked the recource option

2) remove/comment the _isAllowed() method  body from controller file.
like below.
 
     
    protected function _isAllowed()
    {
        return $this->_authorization->isAllowed('Vendor_ModuleName::Resource');
    }