Civil 3D 2018 to ACA 2013

We have started to get drawings from Civil consultants in the 2018 file format. Thanks to our recent move to the AEC Collection, we now have access to AutoCAD^® Civil 3D^®. I have no idea how to use that program, beyond the AutoCAD basics, but I installed the 2018 version of it in the hope that I would be able to export the received drawing to "vanilla" AutoCAD^®. Similar to AutoCAD^® Architecture and AutoCAD^® MEP, you can go to the Application Menu > Export > Export Civil 3D Drawing to export a drawing. There is a dialog, where you can choose between AutoCAD DWG and Microstation^® DGN, and, for DWG export, the Export Settings allow you to select a file format, such as 2013.

I did all of that, and Civil 3D did its thing, and drawings were generated. (I got more than one because I left the Include sheets toggle checked, so a drawing for each layout was also generated.) I fired up AutoCAD Architecture 2016 and opened the exported "Model" file, only to be greeted by this dialog:

What?! I just exported this file to a previous file format - there should not be ANY AEC objects, let alone future ones. I closed the dialog and tried run the WALLADD command. No dice - "Command not allowed because drawing contains objects from a newer version of this application." appeared at the command line. So this drawing, supposedly exported to the previous file format, can be opened, but is otherwise mostly useless. You can externally reference the file and use AEC commands in the host file, saving it from being totally useless.

Still, I expected to have a "clean" 2013-format file that only has non-AEC AutoCAD objects. I tried a Window selection in Model Space to get all the visible objects and then tried to copy them to the clipboard, hoping that if I pasted them in a new file, the future AEC Objects would not come along for the ride. That did not work, as the copy to clipboard failed.

Then I tried to select the Model Space objects and use the WBLOCK command, again hoping that the future AEC Objects would be left behind. That also failed.

Finally, I opened the file in AutoCAD Architecture 2018 and tried to use the AECEXPORTTOAUTOCAD2013 command, in the somewhat desperate hope that might work. I got the following dialog indicating that an error had occurred during the save.

And then this dialog showed up, to rub salt into the wound. I tried "saving" as AutoCAD-only objects!

This was followed by a second showing of the warning dialog recommending the use of the RECOVER command. Opening this file in AutoCAD Architecture 2016 resulted in the same Open Drawing - New Versions of Objects in Drawing dialog as shown in the first image above.

Finally, I tried starting a new drawing and using the INSERT command to insert the originally exported "Model" drawing file. I received the following dialog:

The small-print statement "Newer AEC objects will be disallowed from participating in this operation" gave me hope, as it was not flat-out refusing to do the insertion, and I did not want the newer objects in the file. That hope was confirmed, as it did insert what appeared to be all of the objects that were visible in the exported file, and I was able to add AEC objects to the file. Upon saving and reopening, there were no dialogs chastising me for having a file with future AEC Objects in it. Success! I still think that the original export should have been AEC-object-free, and object to having to go to the extra step of inserting the exported file into an empty file to get rid of the future objects, but at least I have a workaround for providing a "clean" file in the 2013 format that does not require proxy objects or object enablers.