When opening a DWG file with AutoDesk AutoCAD, you see the following error message:
Non Autodesk DWG
This is not a panic error. AutoDesk adds a check to all the DWG files created by its own products. For those created by third-party products, if it cannot pass the check, then AutoCAD will report the above error when opening the files.
You can use our product DataNumen DWG Recovery to repair the DWG file and produce a DWG file that will pass the check and never produce the error again.