Problem: File extensions for CAD drawings cannot be renamed in ArcCatalog
Renaming the file extension of a CAD drawing in ArcCatalog always appends the original file extension. This results in the CAD drawing possessing two file extensions. For example, attempting to rename ‘buildings.dwg’ to ‘buildings.cad’ results in ‘buildings.cad.dwg’.
This is a known issue.
Solution or Workaround
Use Windows Explorer to rename the file extension of a CAD drawing.