Paypal IPN Simulator always returns INVALID despite the correct postback

Question

We are in the process of updating our IPN using TLS and constantly get INVALID sent back when using the IPN simulator

As soon as the request arrives at the listener, it is registered. Before returning data to paypal URL and data are recorded. This information is provided below.

There is nothing wrong with the data. I even used diffmerge to determine that there are no differences other than cmd = _notify-validate &

Is it that IPN Simulator never returns?

---

URL before request:

https://www.sandbox.paypal.com/cgi-bin/webscr

---

Published data

cmd=_notify-validate&payment_type=instant&payment_date=Mon May 23 2016 17:41:16 GMT 1000 (E. Australia Standard Time)&payment_status=Completed&address_status=confirmed&payer_status=verified&first_name=John&last_name=Smith&payer_email=[e-mail]&payer_id=TESTBUYERID01&address_name=John Smith&address_country=United States&address_country_code=US&address_zip=95131&address_state=CA&address_city=San Jose&address_street=123 any street&business=[e-mail]&receiver_email=[e-mail]&receiver_id=[e-mail]&residence_country=US&item_name=something&item_number=CHIMPREWRITER-LIFE&quantity=1&shipping=3.04&tax=2.02&mc_currency=USD&mc_fee=0.44&mc_gross=139&mc_gross_1=139&txn_type=web_accept&txn_id=928133899&notify_version=2.1&custom=xyz123&invoice=abc1234&test_ipn=1&verify_sign=AFcWxV21C7fd0v3bYYYRCpSSRl31AU-9VToMcj-IcSKMfmb8nz2kgIe.

---

Data from Paypal

payment_type=instant&payment_date=Mon May 23 2016 17:41:16 GMT 1000 (E. Australia Standard Time)&payment_status=Completed&address_status=confirmed&payer_status=verified&first_name=John&last_name=Smith&payer_email=[e-mail]&payer_id=TESTBUYERID01&address_name=John Smith&address_country=United States&address_country_code=US&address_zip=95131&address_state=CA&address_city=San Jose&address_street=123 any street&business=[e-mail]&receiver_email=[e-mail]&receiver_id=[e-mail]&residence_country=US&item_name=something&item_number=CHIMPREWRITER-LIFE&quantity=1&shipping=3.04&tax=2.02&mc_currency=USD&mc_fee=0.44&mc_gross=139&mc_gross_1=139&txn_type=web_accept&txn_id=928133899&notify_version=2.1&custom=xyz123&invoice=abc1234&test_ipn=1&verify_sign=AFcWxV21C7fd0v3bYYYRCpSSRl31AU-9VToMcj-IcSKMfmb8nz2kgIe.

---

For reference, code:

// This was legacy code I was trying in case there were formatting problems. The code "cmd=_notify-validate&" + _request.Form; does some URL encoding which I thought might be causing problems. Either way, we still get INVALID
string s = "cmd=_notify-validate";
foreach (string paramName in _request.Form)
{
    string paramValue = LicServiceTools.Encode(_request.Form[paramName]);
    //s = s + string.Format("&{0}={1}", paramName, paramValue);
    s = s + string.Format("&{0}={1}", paramName, _request.Form[paramName]);
}

string address = "https://www.paypal.com/cgi-bin/webscr";
if (this.useSandBox)
{
    address = "https://www.sandbox.paypal.com/cgi-bin/webscr";
}
System.Net.ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;
HttpWebRequest req = (HttpWebRequest)WebRequest.Create(address);
req.ProtocolVersion = HttpVersion.Version11;
//Set values for the request back
req.Method = "POST";
req.ContentType = "application/x-www-form-urlencoded";

// ALSO DOESNT WORK
//string strRequest = "cmd=_notify-validate&" + _request.Form;
//req.ContentLength = strRequest.Length;

errorLogger.Info(s);
errorLogger.Info(address);

//Send the request to PayPal and get the response
StreamWriter streamOut = new StreamWriter(req.GetRequestStream(), System.Text.Encoding.ASCII);
streamOut.Write(s);
streamOut.Close();
StreamReader streamIn = new StreamReader(req.GetResponse().GetResponseStream());
string strResponse = streamIn.ReadToEnd();
streamIn.Close();

// at this point, strResponse = INVALID

Answer 1

, IPN payment_date - "+" . , , .

: https://github.com/paypal/ipn-code-samples/issues/51