请求被中止：无法创建 SSL/TLS 安全通道。

我想实现 Paypal dodirect 方法，让用户可以直接在我的网站上付款，而不是重定向到用户

因此我已将此 URL 添加为https://www.sandbox.paypal.com/wsdl/PayPalSvc.wsdl https://www.sandbox.paypal.com/wsdl/PayPalSvc.wsdl

我正在使用以下代码

PayPalAPIAAInterfaceClient objpaypalapiaainterfaceclient = new PayPalAPIAAInterfaceClient("paypalapiaa");
        CustomSecurityHeaderType objcustomsecurityheadertype = new CustomSecurityHeaderType();
        objcustomsecurityheadertype.Credentials = new UserIdPasswordType();
        objcustomsecurityheadertype.Credentials.Signature = "a8ft-8ji.2tzocnfshfjj4ahgxn4avlxzply8bmsbupxafkbty2--c6p";
        objcustomsecurityheadertype.Credentials.Username = "fred_1350925179_biz_api1.gmail.com";
        objcustomsecurityheadertype.Credentials.Password = "1350925199";

        DoDirectPaymentReq objdodirectpaymentreq = new DoDirectPaymentReq();
        objdodirectpaymentreq.DoDirectPaymentRequest = new DoDirectPaymentRequestType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails = new DoDirectPaymentRequestDetailsType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.PaymentAction = new PaymentActionCodeType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.PaymentAction = PaymentActionCodeType.Sale;
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.PaymentDetails = new PaymentDetailsType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard = new CreditCardDetailsType();
        //objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.PaymentDetails.InvoiceID = "1";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.IPAddress = Request.ServerVariables["remote_addr"].ToString();

        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CreditCardType = CreditCardTypeType.MasterCard;

        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.PaymentDetails.OrderTotal = new BasicAmountType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner = new PayerInfoType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.PayerName = new PersonNameType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.PaymentDetails.OrderTotal.currencyID = CurrencyCodeType.USD;
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.Address = new AddressType();
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.PaymentDetails.OrderTotal.Value = "120";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CreditCardNumber ="1111222233334444";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CVV2 = "258";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.ExpMonth = 9;
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.ExpYear = 2013;
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.Payer = "[email protected] /cdn-cgi/l/email-protection";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.PayerName.FirstName = "Shakti";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.PayerName.LastName = "Kapoor";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.Address.Street1 ="test address";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.Address.CityName = "Atlanta";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.Address.StateOrProvince = "ga";
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.Address.Country = CountryCodeType.US;
        objdodirectpaymentreq.DoDirectPaymentRequest.DoDirectPaymentRequestDetails.CreditCard.CardOwner.Address.PostalCode = "12345";
        DoDirectPaymentResponseType objdodirectpaymentresponsetype = objpaypalapiaainterfaceclient.DoDirectPayment(ref objcustomsecurityheadertype, objdodirectpaymentreq);

现在当我运行此代码时抛出以下异常

' 请求被中止：无法创建 SSL/TLS 安全通道。 描述：执行当前 Web 请求期间发生未处理的异常。请查看堆栈跟踪以获取有关错误及其在代码中的来源的更多信息。 异常详细信息：System.Net.WebException：请求已中止：无法创建 SSL/TLS 安全通道。

You can confirm the SSL protocol for https://www.sandbox.paypal.com https://www.sandbox.paypal.com, using https://www.ssllabs.com/ssltest https://www.ssllabs.com/ssltest. The screenshot shows that it supports TLS 1.2 You will need to add the following two lines to your code at the point of making httpclient call:

ServicePointManager.Expect100Continue = true; ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

Sample: The implementation should solve the problem.