Hi there,
I see this when opening a file save from Solid Works or some other program. Even after opening the file, say a Solid Works dxf for example, open and edit in ACE then save as DWG I still see this message the next time I open the file. Try to Continue Open and see what you get.
Good luck
Non Autodesk DWG. This DWG file was saved by a software application that was not developed or licensed by Autodesk. Autodesk cannot guarantee the application compatibility or integrity of this file.
This happens with ALL AutoCAD Electrical DWGs, ACAD LT 2016 DWGs - EVERY DWG file. We only use Autodesk products here. All I did was install AutoCAD Electrical 2018.