I'm trying to export images from Lib.When the size exceeds 5000*5000, it shows "Export failed!".Unluckily, I want to export a big image approximately 8000*8000. So anyone know how to create a big image or there is a limitation for exporting. But, for real, 5000*5000 is not a very big image today.
Indeed LibreCAD fails exporting large images as you described.
But exporting as image is faulty anyway as LC doesn't show lineweights properly.
I recommend to export as pdf and then convert to image in inkscape or similar program.