我是 PayPal SDK 的新手，正在尝试在 Laravel 应用程序中使用 PayPal Checkout SDK。

我已按照以下 github 页面 中的大部分说明进行操作，第一次调用 create-payment 函数似乎有效；但是，当我在 PayPal 弹出窗口上按下继续来执行交易时，它会失败并产生以下错误：

Error: Request to post /api/execute-payment failed with 500 error. Correlation id: unknown
    {
        "message": "Got Http response code 400 when accessing https://api.sandbox.paypal.com/v1/payments/payment/PAY-3RB62059V6076291ALRCHT6Y/execute.",
        "exception": "PayPal\\Exception\\PayPalConnectionException",
        "file": "C:\\websites\\online-webstore\\vendor\\paypal\\rest-api-sdk-php\\lib\\PayPal\\Core\\PayPalHttpConnection.php",
        "line": 207, {...} 

检查链接： https://api.sandbox.paypal.com/v1/payments/payment/PAY-3RB62059V6076291ALRCHT6Y/execute ，我收到错误：

{"name":"AUTHENTICATION_FAILURE","message":"Authentication failed due to invalid authentication credentials or a missing Authorization header.","links":[{"href":"https://developer.paypal.com/docs/api/overview/#error","rel":"information_link"}]}

这是我的设置，因此对于客户端：

<script src="https://www.paypalobjects.com/api/checkout.js"></script>

  <div id="paypal-button"></div>

  <script>
    paypal.Button.render({
      env: 'sandbox', // Or 'production'
      // Set up the payment:
      // 1. Add a payment callback
      payment: function(data, actions) {
        // 2. Make a request to your server
        return actions.request.post('/api/create-payment')
          .then(function(res) {
            // 3. Return res.id from the response
            return res.id;
          });
      },
      // Execute the payment:
      // 1. Add an onAuthorize callback
      onAuthorize: function(data, actions) {
        // 2. Make a request to your server
        return actions.request.post('/api/execute-payment', {
          paymentID: data.paymentID,
          payerID:   data.payerID
        })
          .then(function(res) {
              console.log(res);
              alert('PAYMENT WENT THROUGH!!');
          }).catch(function(err){
            console.log("Error "+err);
          });
      }
    }, '#paypal-button');
  </script>

在我的控制器中设置如下所以：

class CheckoutController extends Controller
{

    private $apiContext;
    private $client_id;
    private $secret;

    public function __construct()
    {
        $this->middleware('auth', ['except'=>['createPayment', 'executePayment']]);

        // Detect if we are running in live mode or sandbox
        if(config('paypal.settings.mode') == 'live'){
            $this->client_id = config('paypal.live_client_id');
            $this->secret = config('paypal.live_secret');
        } else {
            $this->client_id = config('paypal.sandbox_client_id');
            $this->secret = config('paypal.sandbox_secret');
        }

        // Set the Paypal API Context/Credentials
        $this->apiContext = new ApiContext(new OAuthTokenCredential($this->client_id, $this->secret));
        $this->apiContext->setConfig(config('paypal.settings'));
    }

    public function createPayment () {
        $payer = new Payer();
        $payer->setPaymentMethod("paypal");

        $item1 = new Item();
        $item1->setName('Ground Coffee 40 oz')
            ->setCurrency('USD')
            ->setQuantity(1)
            ->setSku("123123") // Similar to `item_number` in Classic API
            ->setPrice(7.5);
        $item2 = new Item();
        $item2->setName('Granola bars')
            ->setCurrency('USD')
            ->setQuantity(5)
            ->setSku("321321") // Similar to `item_number` in Classic API
            ->setPrice(2);

        $itemList = new ItemList();
        $itemList->setItems(array($item1, $item2));

        $details = new Details();
        $details->setShipping(1.2)
            ->setTax(1.3)
            ->setSubtotal(17.50);

        $amount = new Amount();
        $amount->setCurrency("USD")
        ->setTotal(20)
        ->setDetails($details);

        $transaction = new Transaction();
        $transaction->setAmount($amount)
        ->setItemList($itemList)
        ->setDescription("Payment description")
        ->setInvoiceNumber(uniqid());

        $baseUrl = \URL::to('/');
        $redirectUrls = new RedirectUrls();
        $redirectUrls->setReturnUrl("http://online-webstore/paypalRedirect/true")
        ->setCancelUrl("http://online-webstore/paypalRedirect/false");

        $payment = new Payment();
        $payment->setIntent("sale")
        ->setPayer($payer)
        ->setRedirectUrls($redirectUrls)
        ->setTransactions(array($transaction));

        $request = clone $payment;

        try {
        $payment->create($this->apiContext);
        } catch (Exception $ex) {
            exit(1);
        }

        $approvalUrl = $payment->getApprovalLink();

        return $payment;
    }

    public function executePayment (Request $request) {

        $paymentId = $request->paymentID;
        $payment = Payment::get($paymentId, $this->apiContext);

        $execution = new PaymentExecution();
        $execution->setPayerId($request->PayerID);

        try {
            $result = $payment->execute($execution, $this->apiContext);
        } catch (PayPal\Exception\PayPalConnectionException $ex) {
           echo $ex->getData(); // Prints the detailed error message 
           die($ex);
        }

        return $result;
    }

}

我还正确地将我的凭证包含在我的 .env 文件中，并在沙盒模式下运行它。

有人可以告诉我哪里可能出错了，如果需要，我很乐意提供更多信息。