diff --git a/lib/Config/PublicAPI.php b/lib/Config/PublicAPI.php
index 5ef8e206ad..b03e2e4fb4 100644
--- a/lib/Config/PublicAPI.php
+++ b/lib/Config/PublicAPI.php
@@ -20,7 +20,7 @@ class PublicAPI {
       Helpers::underscoreToCamelCase($_GET['action']) :
       false;
     $this->request_payload = isset($_GET['request_payload']) ?
-      json_decode(urldecode($_GET['request_payload']), true) :
+      unserialize(base64_decode($_GET['request_payload'])) :
       false;
   }
 
diff --git a/lib/Cron/Daemon.php b/lib/Cron/Daemon.php
index fa0294acfc..b2307ab474 100644
--- a/lib/Cron/Daemon.php
+++ b/lib/Cron/Daemon.php
@@ -112,23 +112,27 @@ class Daemon {
 
   function manageSession($action) {
     switch($action) {
-    case 'start':
-      if(session_id()) {
+      case 'start':
+        if(session_id()) {
+          session_write_close();
+        }
+        session_id($this->request_payload['session']);
+        session_start();
+        if (!isset($_SESSION['cron_daemon'])) {
+          throw new \Exception(__('Session cannot be read.'));
+        }
+        break;
+      case 'end':
         session_write_close();
-      }
-      session_id($this->request_payload['session']);
-      session_start();
-    break;
-    case 'end':
-      session_write_close();
-    break;
+        break;
     }
   }
 
   function callSelf() {
-    $payload = json_encode(array('token' => $this->refreshed_token));
+    $payload = serialize(array('token' => $this->refreshed_token));
     Supervisor::accessRemoteUrl(
-      '/?mailpoet-api&section=queue&action=run&request_payload=' . urlencode($payload)
+      '/?mailpoet-api&section=queue&action=run&request_payload=' .
+      base64_encode($payload)
     );
     exit;
   }
diff --git a/lib/Cron/Supervisor.php b/lib/Cron/Supervisor.php
index 224e3cbcc9..532a7c5e00 100644
--- a/lib/Cron/Supervisor.php
+++ b/lib/Cron/Supervisor.php
@@ -51,12 +51,15 @@ class Supervisor {
     $sessionId = session_id();
     session_write_close();
     $_SESSION['cron_daemon'] = null;
-    $requestPayload = json_encode(array('session' => $sessionId));
+    $requestPayload = serialize(array('session' => $sessionId));
     self::accessRemoteUrl(
       '/?mailpoet-api&section=queue&action=start&request_payload=' .
-      urlencode($requestPayload)
+      base64_encode($requestPayload)
     );
     session_start();
+    if (!isset($_SESSION['cron_daemon'])) {
+      throw new \Exception(__('Session cannot be read.'));
+    }
     $daemonStatus = $_SESSION['cron_daemon'];
     unset($_SESSION['daemon']);
     session_write_close();