Save Early - Save Often

I thought that was a mantra only for AutoCAD.  It is TRUE for LibreCAD too.  I have not found the autoSAVE setting in LibreCAD - if there is one.  Hence, after thirty (30) minutes of significant Fillet mods with circles, ellipses, and lines, LibreCAD decides to "get confused" and shut down, I lose!  Oh well.  Some days are better than others.  Live and learn.

#***.dxf and ***.dxf~ are backup files. Remove the ~ or #.
Auto back up settings are in Options - Application Preferences - Defaults.

True for LibreCAD and for other applications.

My tip: incremental saves !
Save every 10 / 15 minutes using a version number at the end of file name -> xxxx_01.dxf
You cannot lose more that the work done since the last save.
Advantage: if you make non-recoverable mistake you can revert to previous save.
Done with you work ? Then delete unnecessary former saves.