Illuminate\Routing\Redirector::back PHP Method

    public function back($status = 302, $headers = [], $fallback = false)
    {
        $back = $this->generator->previous($fallback);
        return $this->createRedirect($back, $status, $headers);
    }

 /**
  * @param  string $middleware
  * @param  bool   $isAjax
  * @return \Illuminate\Http\RedirectResponse
  */
 protected function failedResponse($middleware, $isAjax = false)
 {
     if ($isAjax) {
         return $this->response->make($this->getErrorMessage($middleware), 403);
     }
     return $this->redirector->back()->exceptInput('_guard_pot', '_guard_opened')->withErrors($this->getErrorMessage($middleware));
 }