System service lost from API DOCS

My upgraded instance of DF2, dont have more the SYSTEM SERVICE in API DOCS

Admin Application Version: 2.1.6
DreamFactory Version: 2.1.2

Operating System: linux
Release: 3.16.0-4-amd64
version: #1 SMP Debian 3.16.7-ckt11-1 (2015-05-24)
Machine: x86_64

in log file

local.ERROR: * System error creating swagger file for service ‘system’.
Service configuration class name lookup failed for resource DreamFactory\Core\Resources\System\Setting