C＃-PayPal Checkout JSON.Stringify“无法加载响应...错误400：错误的请求”

Question

我可以在警报屏幕中看到有关付款的详细信息，并且PayPal沙箱帐户根据收到付款，但是我无法在ASP.NET Core 2.1代码中捕获这些详细信息以记录在数据库中。

                        <div id="paypal-button-container"></div>
                        <script>
                        paypal.Buttons({
                           createOrder: function (data, actions) {
                               return actions.order.create({
                                  purchase_units: [{
                                      amount: {
                                      value: '@planoPreco'
                                      }
                                  }]
                               });
                           },
                           onApprove: function (data, actions) {
                               return actions.order.capture().then(function (details) {
                                   alert('Transação completada por ' +
                                       details.payer.email_address + '\n' +
                                       details.id + '\n' +
                                       details.payer.name.given_name + '\n' + "R$ " +
                                       details.purchase_units[0].amount.value)
                                   return fetch('/Anunciantes/Contrato_Selecionado', {
                                       method: 'post',
                                       body: JSON.stringify({
                                           orderID: details.payer.email_address// '50007000'// data.orderID
                                       })
                                   })
                               });
                           }
                        }).render('#paypal-button-container');
                        </script>


    public async Task<IActionResult> OnPostAsync([FromBody] string orderID)
    {
        Console.Beep();

        TempData["Message"] = "Pagamento Salvo";

        var user = await UserManager.FindByIdAsync("10");

    }