PayPal API Http调用问题

Question

I've integrated an option for users to pay via PayPal their online shopping on the web shop that I'm creating. The problem came up suddenly when I started to get this error:

You must write ContentLength bytes to the request stream before calling [Begin]GetResponse. 

And the code for the Http call is as following:

   public string HttpCall(string NvpRequest)
        {
            string url = pEndPointURL;

            string strPost = NvpRequest + "&" + buildCredentialsNVPString();
            strPost = strPost + "&BUTTONSOURCE=" + HttpUtility.UrlEncode(BNCode);

            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.ToString());
                }
            }
            catch (Exception e)
            {

            }

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

            return result;
        }

Can someone help me out with this? It worked fine a day ago, now its giving me this error?

Answer 1

Okay so if anyone is interested, I was able to fix the error by adding the following line before creating the web request (I was able to fix it by going down to Tls12 like this):

`ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12`;

Cheers :-)

Edit try this:

 public string HttpCall(string NvpRequest)
    {
        string url = pEndPointURL;

        string strPost = NvpRequest + "&" + buildCredentialsNVPString();
        strPost = strPost + "&BUTTONSOURCE=" + HttpUtility.UrlEncode(BNCode);
        ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls;
        // Try using Tls11 if it doesnt works for you with Tls
        HttpWebRequest objRequest = (HttpWebRequest)WebRequest.Create(url);
        objRequest.Timeout = Timeout;
        objRequest.Method = WebRequestMethods.Http.Post;
        objRequest.ContentLength = strPost.Length;
        try
        {

            using (StreamWriter myWriter = new StreamWriter(objRequest.GetRequestStream()))
            {
                myWriter.Write(strPost.ToString());
            }
        }
        catch (Exception e)
        {

        }

        //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();
        }

        return result;
    }

Answer 2

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 );

    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 3

经过几个小时的浪费，结果证明是Tls协议版本。

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;