diff --git a/common.php b/common.php
index 0a3930ab9..3accb2512 100644
--- a/common.php
+++ b/common.php
@@ -339,8 +339,10 @@ if( $config['cf_cert_use'] || (defined('G5_YOUNGCART_VER') && G5_YOUNGCART_VER)
             $res = @session_start($options);
 
             // IE 브라우저 또는 엣지브라우저 또는 IOS 모바일과 http환경에서는 secure; SameSite=None을 설정하지 않습니다.
-            if( preg_match('/Edge/i', $_SERVER['HTTP_USER_AGENT']) || preg_match('/(iPhone|iPod|iPad).*AppleWebKit.*Safari/i', $_SERVER['HTTP_USER_AGENT']) || preg_match('~MSIE|Internet Explorer~i', $_SERVER['HTTP_USER_AGENT']) || preg_match('~Trident/7.0(; Touch)?; rv:11.0~',$_SERVER['HTTP_USER_AGENT']) || ! (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS']=='on') ){
-                return $res;
+            if (isset($_SERVER['HTTP_USER_AGENT'])) {
+                if( preg_match('/Edge/i', $_SERVER['HTTP_USER_AGENT']) || preg_match('/(iPhone|iPod|iPad).*AppleWebKit.*Safari/i', $_SERVER['HTTP_USER_AGENT']) || preg_match('~MSIE|Internet Explorer~i', $_SERVER['HTTP_USER_AGENT']) || preg_match('~Trident/7.0(; Touch)?; rv:11.0~',$_SERVER['HTTP_USER_AGENT']) || ! (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS']=='on') ){
+                    return $res;
+                }
             }
 
             $headers = headers_list();