diff --git a/auth/linkedin/callback.php b/auth/linkedin/callback.php
index b8fec58..e30d0dd 100644
--- a/auth/linkedin/callback.php
+++ b/auth/linkedin/callback.php
@@ -8,6 +8,8 @@
 
 require_once "./function.php";
 
+session_start();
+
 $state = 'x1Dr3Nu0AaxM1TuLVuGwAJWM';
 
 // step 1: get access token by code