.net - 请求被中止 : Could not create SSL/TLS secure channel sandbox account

Question

它在一周前运行良好，但现在显示以下错误。我尝试了以下方法但没有用。

ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;

所以建议我可能的解决方案

public string HttpCall(string NvpRequest) //CallNvpServer
    {
        string url = pendpointurl;

        //To Add the credentials from the profile
        string strPost = NvpRequest + "&" + buildCredentialsNVPString();
        strPost = strPost + "&BUTTONSOURCE=" + HttpUtility.UrlEncode(BNCode);

        ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3;
        // allows for validation of SSL conversations
        ServicePointManager.ServerCertificateValidationCallback = delegate { return true; };


        HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(url);
        objRequest.Timeout = Timeout;
        objRequest.Method = "POST";
        objRequest.ContentLength = strPost.Length;

        try
        {
            using (StreamWriter myWriter = new StreamWriter(objRequest.GetRequestStream()))
            {
                myWriter.Write(strPost);
            }
        }
        catch (Exception e)
        {
            /*
            if (log.IsFatalEnabled)
            {
                log.Fatal(e.Message, this);
            }*/
        }

        //Retrieve the Response returned from the NVP API call to PayPal
        HttpWebResponse objResponse = (HttpWebResponse)objRequest.GetResponse();
        string result;
        using (StreamReader sr = new StreamReader(objResponse.GetResponseStream()))
        {
            result = sr.ReadToEnd();
        }

        //Logging the response of the transaction
        /* if (log.IsInfoEnabled)
         {
             log.Info("Result :" +
                       " Elapsed Time : " + (DateTime.Now - startDate).Milliseconds + " ms" +
                      result);
         }
         */
        return result;
    }

Answer 1

我刚刚在我的测试环境中也遇到了同样的问题(幸运的是我的实时付款正在进行中)。我通过更改修复了它:

public PayPalAPI(string specialAccount = "")
{
    System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls;

到

public PayPalAPI(string specialAccount = "")
{
    System.Net.ServicePointManager.SecurityProtocol = System.Net.SecurityProtocolType.Tls12;

他们不久前禁用了对 SSL3 的支持:https://www.paypal.com/uk/webapps/mpp/ssl-security-update ，具体说明

Ensure you are connecting to PayPal endpoints using TLS 1.0 or 1.2 (not all API endpoints currently support TLS 1.1).

他们的 latest update (感谢来自@awesome 的评论更新)状态:

PayPal is updating its services to require TLS 1.2 for all HTTPS connections. At this time, PayPal will also require HTTP/1.1 for all connections... To avoid any disruption of service, you must verify that your systems are ready for this change by June 17, 2016