Hi, my IPN listener stopped working recently and I'm not sure why.  I scaled down my listener to bare bones just to see if it receives the IPN but when I try to log, I get nothing.  I have an SSL cert with GoDaddy and when I test locally using an html form, it seems to work.  I get INVALID of course because it's not from Paypal, it's from my own web form.  When I resend IPNs to my listener, however, I never get an HTTP response.  It's blank.  This has been driving me crazy for last week.  If anyone can please help, it would be much appreciated.


This is my listener (URL listed in profile IPN settings with https):






function writeToLog($text) {
	$handle = fopen('log.txt', 'a');
	if ($handle) {
		$logData = "\n\n----[" . date('Y-m-d') . ' ' . date('H:i:s') . "]-------------\n";
		$logData .= $text;
		fwrite($handle, $logData);
//file_put_contents("log_paypal.txt", print_r("POST: ".file_get_contents("php://input"), true));
//writeToLog("POST2: ".$_POST['payer_id']);
//use PaypalIPN;

$ipn = new PaypalIPN();

// Use the sandbox endpoint during testing.
$verified = $ipn->verifyIPN();

if (!$verified) {
     * Process IPN
     * A list of variables is available here:
     * https://developer.paypal.com/webapps/developer/docs/classic/ipn/integration-guide/IPNandPDTVariables/

// Reply with an empty 200 response to indicate to paypal the IPN was received correctly.
header("HTTP/1.1 200 OK");
//echo "done";




Listener class:



class PaypalIPN
    /** @Var bool Indicates if the sandbox endpoint is used. */
    private $use_sandbox = false;
    /** @Var bool Indicates if the local certificates are used. */
    private $use_local_certs = false;

    /** Production Postback URL */
    const VERIFY_URI = 'https://ipnpb.paypal.com/cgi-bin/webscr';
    /** Sandbox Postback URL */
    const SANDBOX_VERIFY_URI = 'https://ipnpb.sandbox.paypal.com/cgi-bin/webscr';

    /** Response from PayPal indicating validation was successful */
    const VALID = 'VERIFIED';
    /** Response from PayPal indicating validation failed */
    const INVALID = 'INVALID';

     * Sets the IPN verification to sandbox mode (for use when testing,
     * should not be enabled in production).
     * @RETURN void
    public function useSandbox()
        $this->use_sandbox = true;

     * Sets curl to use php curl's built in certs (may be required in some
     * environments).
     * @RETURN void
    public function usePHPCerts()
        $this->use_local_certs = false;

     * Determine endpoint to post the verification data to.
     * @RETURN string
    public function getPaypalUri()
        if ($this->use_sandbox) {
            return self::SANDBOX_VERIFY_URI;
        } else {
            return self::VERIFY_URI;

     * Verification Function
     * Sends the incoming post data back to PayPal using the cURL library.
     * @RETURN bool
     * @throws Exception
    public function verifyIPN()
		if (! count($_POST)) {
		writeToLog("no count");

        $raw_post_data = file_get_contents('php://input');
        $raw_post_array = explode('&', $raw_post_data);
        $myPost = array();
        foreach ($raw_post_array as $keyval) {
            $keyval = explode('=', $keyval);
            if (count($keyval) == 2) {
                // Since we do not want the plus in the datetime string to be encoded to a space, we manually encode it.
                if ($keyval[0] === 'payment_date') {
                    if (substr_count($keyval[1], '+') === 1) {
                        $keyval[1] = str_replace('+', '%2B', $keyval[1]);
                $myPost[$keyval[0]] = rawurldecode($keyval[1]);

        // Build the body of the verification post request, adding the _notify-validate command.
        $req = 'cmd=_notify-validate';

        foreach ($myPost as $key => $value) {
            $value = rawurlencode($value);
            $req .= "&$key=$value";

        // Post the data back to PayPal, using curl. Throw exceptions if errors occur.
        $ch = curl_init($this->getPaypalUri());
        curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
        curl_setopt($ch, CURLOPT_POST, 1);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
        curl_setopt($ch, CURLOPT_SSLVERSION, 6);
        curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
        curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);

        // This is often required if the server is missing a global cert bundle, or is using an outdated one.
        if ($this->use_local_certs) {
            curl_setopt($ch, CURLOPT_CAINFO, __DIR__ . "/cert/cacert.pem");
        curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
        curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 30);
        curl_setopt($ch, CURLOPT_HTTPHEADER, array(
            'User-Agent: PHP-IPN-Verification-Script',
            'Connection: Close',
        $res = curl_exec($ch);
        if ( ! ($res)) {
            $errno = curl_errno($ch);
            $errstr = curl_error($ch);
            throw new Exception("cURL error: [$errno] $errstr");
        $info = curl_getinfo($ch);
        $http_code = $info['http_code'];
        if ($http_code != 200) {
            throw new Exception("PayPal responded with http code $http_code");


        // Check if PayPal verifies the IPN data, and if so, return true.
        if ($res == self::VALID) {
            return true;
        } else {
            return false;




This is what I keep seeing in IPN history:














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Good day @rightway77 


Thank you for posting to the PayPal community.


PayPal system will send the IPN response logs to the specific IPN endpoint URL which merchant passed in their website API request call.


If your(merchant) IPN listener server fails to return HTTP 200 OK response to PayPal POST, system will retry sending the IPN details for 16 times by auto alerting the merchant via email.


Please refer the detailed guide link to resolve the issue -




If you notice many Failed or Retrying entries, it is likely that the reason behind the delay in IPN failure to send HTTP 200 OK responses. To resolve this issue, you should review your server logs to identify why the required HTTP 200 OK responses are not being sent and fix your listener accordingly. Once your listener starts sending the required HTTP 200 OK responses, PayPal will post IPNs from the faster-cycling server.


If your still facing issues, please create an MTS ticket via -  https://www.paypal-support.com/s/?language=en_US  with the detailed information and error details.




PayPal MTS


If this post or any other was helpful, please enrich the community by giving kudos or accepting it as a solution.

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