Error : The requested URL returned error: 409

public static function sendToSingleUser($title, $body, $targetUrl, $id)
{
$end_point = ‘https://api.webpushr.com/v1/notification/send/sid’;
$key = config(‘services.webpushr.webPushrKey’);
$token = config(‘services.webpushr.webPushrToken’);

$http_header = array( 
	"Content-Type: Application/Json", 
	"webpushrKey: $key", 
	"webpushrAuthToken: $token"
);
$req_data = array(
	'title' 			=> $title, //required
	'message' 		=> $body, //required
	'target_url'	=> $targetUrl, //required
	'sid'		=> $id //required
);

print_r($ch); die();
$ch = curl_init();
curl_setopt($ch, CURLOPT_HTTPHEADER, $http_header);
curl_setopt($ch, CURLOPT_URL, $end_point );
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($req_data) );
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_FAILONERROR, true); 
$response = curl_exec($ch);

if(curl_errno($ch)){
	echo 'Request Error:' . curl_error($ch);
}

//var_dump($error_msg); 

curl_close($ch);

}

$req_data and $http_header are correct. But error "The requested URL returned error: 409 " is showing
Can someone plz help me with this

You can see the error codes and their description on this page: API Guide: Send Push Notification to a Subscriber ID - Webpushr

409 is returned when a subscriber is not found. Please make sure you are using a valid SID