Posted by dellus on Mar 08, 2019; 2:28pm
URL: https://forum.librecad.org/DXF-File-Import-Issues-tp5717034p5717035.html

When you "Save as" dxf 2007 is the most recent version offered, so one can assume this is valid for opening also. ASCII or binary, I don't know.
LibreCAD can be picky on the way to open a file, whether from the program or via file. Sometimes "Recent files" work if unsuccessfully tried before.
LibreCAD is very sensitive to hatch outlines not exactly closed, maybe AutoCAD is more forgiving.

LordofBikes knows more about all this, so hopefully he will give you a more satisfying answer.