Convert BAK to ARX

If AutoCAD needs an ARX plug-in but you have only a .bak file, first determine whether that backup was originally an ARX file. A BAK file from a drawing or another application cannot be converted into a plug-in by changing its extension.

What the BAK format is

.bak is a generic backup extension, not a standardized file format. AutoCAD and many other programs create BAK files, and the contents depend on the program that made the backup. An AutoCAD drawing backup is typically a DWG drawing saved with the .bak extension.

What the ARX format is

.arx is AutoCAD’s compiled application-extension format. ARX files contain native plug-in code for compatible Windows versions of full AutoCAD; they are not drawings or archives. Creating an ARX plug-in generally requires its source project and the ObjectARX SDK and compiler versions supported for the target AutoCAD release.

How to restore or create an ARX file

1. Identify the backup’s source. Check its folder, filename, and the application that created it. Show file extensions in your file manager if necessary; a BAK extension alone does not identify the file contents.
2. For an AutoCAD drawing backup, restore a drawing. Make a copy of the BAK file and rename the copy to use .dwg, then open it in AutoCAD. If needed, use Save As to save the drawing in DWG or DXF format. This does not create an ARX plug-in.
3. For a backup of an existing ARX plug-in, restore the original file. Work on a copy and rename .bak to .arx only after confirming that the backup contains that plug-in. Renaming restores the file; it does not convert its contents.
4. To build a new plug-in, use its source project. Install the ObjectARX SDK for the target AutoCAD release, open the project in the Visual Studio version supported by that SDK, select the required build configuration, and build it. The resulting compiled plug-in is an .arx file. A BAK file alone is not a substitute for the source project.

Compatibility and limitations

ARX plug-ins must match the target AutoCAD release and supported build environment; a plug-in built for one release may not load in another. AutoCAD LT does not load ARX plug-ins. There is no general-purpose converter that turns arbitrary BAK data into executable ARX code, and online conversion cannot replace the required source code and build process. Do not upload unknown BAK files to conversion sites: they may contain private data or executable code.