diff --git a/js/src/functions.js b/js/src/functions.js
index 28c1d214a5..1654f17121 100644
--- a/js/src/functions.js
+++ b/js/src/functions.js
@@ -3806,14 +3806,22 @@ AJAX.registerOnload('functions.js', function () {
 
     // Sync favorite tables from localStorage to pmadb.
     if ($('#sync_favorite_tables').length) {
+        var favoriteTables = '';
+        if (isStorageSupported('localStorage')
+            && typeof window.localStorage.favoriteTables !== 'undefined'
+            && window.localStorage.favoriteTables !== 'undefined') {
+            favoriteTables = window.localStorage.favoriteTables;
+            if (favoriteTables === 'undefined') {
+                // Do not send an invalid value
+                return;
+            }
+        }
         $.ajax({
             url: $('#sync_favorite_tables').attr('href'),
             cache: false,
             type: 'POST',
             data: {
-                'favoriteTables': (isStorageSupported('localStorage') && typeof window.localStorage.favoriteTables !== 'undefined')
-                    ? window.localStorage.favoriteTables
-                    : '',
+                'favoriteTables': favoriteTables,
                 'server': CommonParams.get('server'),
                 'no_debug': true
             },