现在需要核对2018年的数据，使用的是开发文档V2版本，下载资金账单接口返回[商户证书不合法]，但是用同样的商户号同样的证书走退款流程却没有问题。请求参数和返回响应信息如下：-->request start { url: https://api.mch.weixin.qq.com/pay/downloadfundflow, method: POST, headers: [ ACCEPT: */*, Content-Type: text/xml;charset=UTF-8, Content-Length: 236, Host: api.mch.weixin.qq.com, Connection: Keep-Alive, Accept-Encoding: gzip, User-Agent: okhttp/3.3.0 ], body: <xml><nonce_str>d1d72a70906d4afebe0b824238849ce2</nonce_str><appid>xxxx</appid><mch_id>xxxx</mch_id><sign>xxxx</sign><bill_date>20180101</bill_date><account_type>Basic</account_type></xml>, protocol: http/1.1 } -->request end  2020-12-14 18:26:20.821 +0800 [payment-api][DEV][INFO] from com.xingren.service.client.interceptors.HttpResponseLogInterceptor in Test worker - [vclient]{}  <--response start { code: 200, msg: OK, url: https://api.mch.weixin.qq.com/pay/downloadfundflow, headers: [ Server: nginx, Date: Mon, 14 Dec 2020 10:26:20 GMT, Content-Type: text/plain; charset=utf-8, Content-Length: 114, Connection: keep-alive, Keep-Alive: timeout=8 ], body: <xml><return_code><![CDATA[FAIL]]></return_code><return_msg><![CDATA[商户证书不合法]]></return_msg></xml>, tookMs: 233ms } 有大佬帮忙解决一下嘛？签名已经用文档里的微信支付接口签名校验工具验证过了，没问题。