.NET Core项目PayPal REST API信用卡支付报错：收款账户无效

在.NET Core项目中使用PayPal REST API 1.9.1，已创建沙箱账户，调用/v1/payments/payment端点进行信用卡支付时出现"Payee account is invalid"错误。切换为PayPal支付方式仅需少量修改即可正常运行，如何让代码支持信用卡支付？

原代码片段 #

string accessToken = new PayPal.Api.OAuthTokenCredential(config).GetAccessToken();
var apiContext = new PayPal.Api.APIContext(accessToken);
// A transaction defines the contract of a payment.
var transaction = new PayPal.Api.Transaction()
{
    amount = new PayPal.Api.Amount()
    {
        currency = "USD",
        total = totalAmount,
        details = new PayPal.Api.Details()
        {
            shipping = shipping,
            subtotal = subTotal,
            tax = tax
        }
    },
    description = description,
    item_list = new PayPal.Api.ItemList()
    {
        items = new List<PayPal.Api.Item>()
        {
            new PayPal.Api.Item()
            {
                name = itemName,
                currency = "USD",
                price = "1",
                quantity = "5",
                sku = "sku"
            }
        },
        shipping_address = new PayPal.Api.ShippingAddress
        {
            city = "Johnstown",
            country_code = "US",
            line1 = "52 N Main ST",
            postal_code = "43210",
            state = "OH",
            recipient_name = "Basher Buyer"
        }
    },
    invoice_number = invoice_number
};
// A resource representing a Payer that funds a payment.
var payer = new PayPal.Api.Payer()
{
    payment_method = "credit_card",
    funding_instruments = new List<PayPal.Api.FundingInstrument>()
    {
        new PayPal.Api.FundingInstrument()
        {
            credit_card = new PayPal.Api.CreditCard()
            {
                billing_address = new PayPal.Api.Address()
                {
                    city = "Johnstown",
                    country_code = "US",
                    line1 = "52 N Main ST",
                    postal_code = "43210",
                    state = "OH"
                },
                cvv2 = card.CVV,
                expire_month = Convert.ToInt32(card.ExpirationMonth),
                expire_year = Convert.ToInt32(card.ExpirationYear),
                first_name = firstName,
                last_name = lastName,
                number = card.CardNumber,
                type = card.CardType
            }
        }
    },
    payer_info = new PayPal.Api.PayerInfo
    {
        email = "test@gmail.com"
    },
};
// A Payment resource; create one using the above types and intent as `sale`, 'order', 'none' or `authorize`
var payment = new PayPal.Api.Payment()
{
    intent = "sale",
    payer = payer,
    transactions = new List<PayPal.Api.Transaction>() { transaction }
};
// Create a payment using a valid APIContext
var createdPayment = payment.Create(apiContext);

解决方案 #

• 启用沙箱商家账户的Payments Pro权限：信用卡直连支付需要商家账户开通PayPal Payments Pro功能。登录PayPal开发者平台，进入沙箱账户管理页面，找到你的商家账户，检查并启用该权限。
• 校验API配置的账户身份：确保config中的客户端ID和密钥属于已开启Payments Pro的沙箱商家账户，而非个人买家账户。
• 移除冗余的payer_info.email字段：使用credit_card支付方式时，该字段非必填，且可能触发账户校验错误，建议删除该部分代码。
• 使用PayPal官方测试信用卡：沙箱环境必须使用官方提供的测试卡号，例如Visa测试卡：4111111111111111，CVV填任意3位，有效期选择未来年份和月份。
• 确保金额计算准确：total必须等于subtotal + shipping + tax的总和，PayPal对金额校验严格，数值不匹配会导致请求失败。

修改后的关键代码片段（移除payer_info） #

var payer = new PayPal.Api.Payer()
{
    payment_method = "credit_card",
    funding_instruments = new List<PayPal.Api.FundingInstrument>()
    {
        new PayPal.Api.FundingInstrument()
        {
            credit_card = new PayPal.Api.CreditCard()
            {
                billing_address = new PayPal.Api.Address()
                {
                    city = "Johnstown",
                    country_code = "US",
                    line1 = "52 N Main ST",
                    postal_code = "43210",
                    state = "OH"
                },
                cvv2 = card.CVV,
                expire_month = Convert.ToInt32(card.ExpirationMonth),
                expire_year = Convert.ToInt32(card.ExpirationYear),
                first_name = firstName,
                last_name = lastName,
                number = card.CardNumber,
                type = card.CardType
            }
        }
    }
};

内容的提问来源于stack exchange，提问作者Tarlok