Error in saving file "Civil Storm in AutoCAD Environment"

Hello A, 

I opened your file in CivilStorm integrated with AutoCAD 2017 platform, but couldn't reproduce the issue there. Added few elements to the model and could save the model with no error message. 

This error message appears to be machine specific and related to AutoCAD, I found something related to this error on AutoCAD forum. 

Are you saving this file at a network location? Please clean temp folder from your system and try again with a different file name. 

Error: "One or more objects in this drawing cannot be saved to the specified format" when saving in AutoCAD 

Please check if this helps or not. 

No, I am saving locally. I tried starting with a new CS file and imported the one i sent you as a sub model and it didn't work.

Import complete but no elements or data brought across. All this happens in CS in AutoCAD. I still saved the file as I moved some of the drawing features (none CS elements) into the new file.

I went on and opened the new file from the stand alone version and did the sub-model import and it worked. Then, I went and opened the same file in AutoCAD version and  it seemed to work! Up on closing and opening, it now features the below, but I guess this is another issue not related to the original problem so let us leave it there. 

I guess I know what has caused the behavior! I found some labels of the StormCAD original catchments that were migrated into CS. I could see those as I unloaded all x-refs and turned CS elements off from element symbology.

I recall the first time I opened the STMC model in CS (if you recall from an earlier post, this model was originally built in STMC), it said that it is migrating data to the corresponding elements or CS elements structure (something along these lines), and once it was done, I still had to edit the catchments as there were some issue with them (I cannot remember what I did but vaguely recall having duplicates and deleting one set).

Anyway, look for these in the CAD file. It sound at some point CAD didn't know what to do with them although it worked fine for while with them present. (In consistent behavior!)