请求alipay.trade.app.pay时302错误？

var alipaySdk = new AlipaySdk(...)后

alisdk.exec('alipay.trade.app.pay', ...) 发生了302错误，返回详情：

{ data: '', status: 302, headers: { server: 'Tengine/2.1.0', date: 'Mon, 02 Dec 2019 08:42:34 GMT', 'content-length': '0', connection: 'keep-alive', 'set-cookie': [Object], location: 'http://openapi.alipay.com/none?alipay_exterface_invoke_assign_target=invoke_6573588deb14af2638cdcaec16e1cd8f&alipay_exterface_invoke_assign_sign=_eixivzzp_n_h_mxs_bqk_v_guk3uxd_a9s_eibx_zl9wiu_yr_qhto_i_k_oo_b1_pir_e_a%3D%3D', via: 'spanner-internet-5206.em14[302]' }, res: { status: 302, statusCode: 302, statusMessage: 'Found', headers: [Object], size: 0, aborted: false, rt: 98, keepAliveSocket: false, .....

请问这个问题要如何解决？签名已经反复验证过多次，应该不是签名问题