diff --git a/workflow/engine/methods/cases/cases_ShowDocument.php b/workflow/engine/methods/cases/cases_ShowDocument.php
index 768e5a814..c5a544c23 100644
--- a/workflow/engine/methods/cases/cases_ShowDocument.php
+++ b/workflow/engine/methods/cases/cases_ShowDocument.php
@@ -1,4 +1,5 @@
 <?php
+
 /**
  * cases_ShowDocument.php
  *
@@ -50,7 +51,7 @@ if (!empty($_SESSION['GUEST_USER']) && $_SESSION['GUEST_USER'] === RBAC::GUEST_U
 }
 $access = $RBAC->userCanAccess('PM_FOLDERS_ALL') != 1 && defined('DISABLE_DOWNLOAD_DOCUMENTS_SESSION_VALIDATION') && DISABLE_DOWNLOAD_DOCUMENTS_SESSION_VALIDATION == 0;
 if ($access && $isGuestUser === false) {
-    if (!$oAppDocument->canDownloadInput($_SESSION['USER_LOGGED'], $_GET['a'], $docVersion)) {
+    if (isset($_SESSION['USER_LOGGED']) && !$oAppDocument->canDownloadInput($_SESSION['USER_LOGGED'], $_GET['a'], $docVersion)) {
         G::header('Location: /errors/error403.php?url=' . urlencode($_SERVER['REQUEST_URI']));
         die();
     }
@@ -131,4 +132,4 @@ if (!$sw_file_exists) {
             G::streamFile($realPath, $bDownload, $nameFile); //download
         }
     }
-}
\ No newline at end of file
+}