https://api.mch.weixin.qq.com/papay/entrustweb&appid=xxx&contract_code=xxxx&contract_display_account=555&mch_id=xxx¬ify_url=www.waquan.com.cn/writ/index.php/index/by_notify&plan_id=xxx&request_serial=16011971354302×tamp=1601197135&version=1.0&sign=00000000
确定下原始字符串是不是你贴出来这样，目测这两处是有问题的