返回错误

New features are all in `APIv3`, there's no reason to continue use this kind client since v2.0.

use WeChatPay\Transformer;
$res = $instance
->v2->mmpaymkttransfers->promotion->transfers
->postAsync([
    'xml' => [
      'mch_appid'        => 'wx8888888888888888',
      'mchid'            => '1900000109',// 注意这个商户号，key是`mchid`非`mch_id`
      'partner_trade_no' => '10000098201411111234567890',
      'openid'           => 'oxTWIuGaIt6gTKsQRLau2M0yL16E',
      'check_name'       => 'FORCE_CHECK',
      're_user_name'     => '王小王',
      'amount'           => '10099',
      'desc'             => '理赔',
      'spbill_create_ip' => '192.168.0.1',
    ],
    'security' => true, //请求需要双向证书
    'debug' => true //开启调试模式
])
->then(static function($response) {
    return Transformer::toArray((string)$response->getBody());
})
->otherwise(static function($e) {
    // 更多`$e`异常类型判断是必须的，这里仅列出一种可能情况，请根据实际对接过程调整并增加
    if ($e instanceof \GuzzleHttp\Promise\RejectionException) {
        return Transformer::toArray((string)$e->getReason()->getBody());
    }
    return [];
})
->wait();
print_r($res);

https://github.com/wechatpay-apiv3/wechatpay-php