Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails , how to fix

Error : (schoolapps_db.vehicles, CONSTRAINT vehicles_driverid_foreign FOREIGN KEY (driverId) REFERENCES drivers (id) ON DELETE CASCADE) Following code show the error :

public function addVehicle(Request $request){

    $vehicle = new vehicle ;
    $vehicle->vehicleCode = $request->vehicleCode ;
    $vehicle->type = $request->type ;
    $vehicle->routeId = $request->routeId ;
    $vehicle->driverId = $request->driverId ;
    $vehicle->status = $request->status ;

    if($vehicle->save()){
        return redirect('/vehicle') ;
    }else{
        return redirect('/vehicle')->with('Operation failed. Please try again.');
    }
}

via Chebli Mohamed