开发云函数遇到 CloudSDKError: errCode: -1 unknown error ？

node.js:1 [error] 函数执行失败（耗时 235ms） CloudSDKError: errCode: -1 unknown error | errMsg: collection.add:fail Error: 

          400 Bad Request

        ; at collection.add api; 

    at returnAsCloudSDKError (D:\badminton.enroll.1.0\cloudfunctions\memberInvest\node_modules\wx-server-sdk\index.js:6086:16)

    at Object.returnAsFinalCloudSDKError (D:\badminton.enroll.1.0\cloudfunctions\memberInvest\node_modules\wx-server-sdk\index.js:6100:15)

    at Promise (D:\badminton.enroll.1.0\cloudfunctions\memberInvest\node_modules\wx-server-sdk\index.js:1198:32)

    at processTicksAndRejections (internal/process/task_queues.js:86:5)