"Drawing file is not valid"

[Anonymous]

Every time I try to open my file it tells me "drawing file is not valid." I attached the file to see if anyone knows how to recover the file.

[David_W_Koch]

I was not able to open it with the RECOVER command, nor was I able to CLASSICINSERT the file, in AutoCAD Architecture 2020.  The attempt to insert the file into a new drawing resulted in this message at the command line:

Command: CLASSICINSERT
** File D:\Downloads\Autodesk DG\AutoCAD Architecture\dallas4net\Nicks drawing.dwg was created by an incompatible version of AutoCAD
*Invalid*

[pendean]

Your posted file appears to be destroyed beyond recovery here too, I tried to open it with non-Autodesk CAD software with the same results: do you have an autosave SV$ or a BAK file (or a backup on your server/backup device) that is usable instead?