I am building a standalone VB app to edit block attribute values. It works fine until I try to save the drawing(s) and ACAD give this message. See attached.
By the way. Only happens when I try to save it from VB. In ACAD I can open and save fine.
Done some research but haven't hit upon the full answer yet.
I've had the same issue, the drawing file is in use by AutoCAD when it's opened and I can't resave it.
My Solution was to make a copy of the file in the users temp folder. open the drawing from that location , make my changes and then save it back to the original location.
Then keep track of the files and then when autocad is closed, delete the copies from the temp folder.
I can post some code if needed.