I don't open kicad file in kicad to ng spice in esim Fossee. I make a schematic of RC circuit in kicad and save a netlist file in kicad. Then a simulate a schematic in ngspice esim Fossee . but when i open kicad to ng spice they seems some error .
you have named your project as TRAIL.cir, the naming convention is wrong. enter only alphanumeric characters as name of the project.
Secondly, before converting the kicad netlist to ngspice netlist, make sure you have indeed generated a .cir netlist file