diff --git a/src/Apn.php b/src/Apn.php
index 3bcee6f..a58df87 100644
--- a/src/Apn.php
+++ b/src/Apn.php
@@ -81,10 +81,14 @@ public function getUnregisteredDeviceTokens(array $devices_token)
      */
     public function send(array $deviceTokens, array $message)
     {
+        if (false == $this->existCertificate()) {
+            return $this->feedback;
+        }
+
         $responseCollection = [
             'success' => true,
-            'errors' => [],
-            'responses' => [],
+            'error' => '',
+            'results' => [],
         ];
 
         if (!$this->curlMultiHandle) {
@@ -151,7 +155,9 @@ public function send(array $deviceTokens, array $message)
 
                 $statusCode = curl_getinfo($handle, CURLINFO_HTTP_CODE);
                 if ($statusCode === 0) {
-                    $responseCollection['errors'][] = [
+                    $responseCollection['success'] = false;
+
+                    $responseCollection['error'] = [
                         'status' => $statusCode,
                         'headers' => $headers,
                         'body' => curl_error($handle),
@@ -162,7 +168,7 @@ public function send(array $deviceTokens, array $message)
 
                 $responseCollection['success'] = $responseCollection['success'] && $statusCode == 200;
 
-                $responseCollection['responses'][] = [
+                $responseCollection['results'][] = [
                     'status' => $statusCode,
                     'headers' => $headers,
                     'body' => (string)$body,
@@ -280,4 +286,39 @@ public function prepareHandle($deviceToken, array $message)
         return $ch;
     }
 
+    /**
+     * Set the feedback with no exist any certificate.
+     *
+     * @return mixed|void
+     */
+    private function messageNoExistCertificate()
+    {
+        $response = [
+            'success' => false,
+            'error' => "Please, add your APN certificate to the iosCertificates folder." . PHP_EOL
+        ];
+
+        $this->setFeedback(json_decode(json_encode($response)));
+    }
+
+    /**
+     * Check if the certificate file exist.
+     * @return bool
+     */
+    private function existCertificate()
+    {
+        if (isset($this->config['certificate'])) {
+            $certificate = $this->config['certificate'];
+            if (!file_exists($certificate)) {
+                $this->messageNoExistCertificate();
+                return false;
+            }
+
+            return true;
+        }
+
+        $this->messageNoExistCertificate();
+        return false;
+    }
+
 }
\ No newline at end of file
diff --git a/src/Gcm.php b/src/Gcm.php
index 56b1664..fe29002 100644
--- a/src/Gcm.php
+++ b/src/Gcm.php
@@ -28,9 +28,9 @@ public function setApiKey($apiKey)
      */
     public function __construct()
     {
-        $this->url = 'https://android.googleapis.com/gcm/send';
-        
-        $this->config = $this->initializeConfig('gcm');
+        $this->url = 'https://fcm.googleapis.com/fcm/send';
+
+        $this->config = $this->initializeConfig('fcm');
         $this->client = new Client;
     }
 
diff --git a/tests/PushNotificationTest.php b/tests/PushNotificationTest.php
index 4ceb626..b8344e3 100644
--- a/tests/PushNotificationTest.php
+++ b/tests/PushNotificationTest.php
@@ -136,21 +136,6 @@ public function apn_without_certificate()
         $this->assertFalse($push->feedback->success);
     }
 
-    /** @test */
-    public function apn_dry_run_option_update_the_apn_url()
-    {
-        $push = new PushNotification('apn');
-
-        $push->setConfig(['dry_run'=>false]);
-
-        $this->assertEquals('ssl://gateway.push.apple.com:2195', $push->url);
-
-        $push->setConfig(['dry_run'=>true]);
-
-        $this->assertEquals('ssl://gateway.sandbox.push.apple.com:2195', $push->url);
-    }
-
-
     /** @test */
     public function fcm_assert_send_method_returns_an_stdClass_instance()
     {