diff --git a/addons/mail/static/src/models/chat_window_manager.js b/addons/mail/static/src/models/chat_window_manager.js
index 01e20877da65f..9d99d6700459b 100644
--- a/addons/mail/static/src/models/chat_window_manager.js
+++ b/addons/mail/static/src/models/chat_window_manager.js
@@ -239,7 +239,7 @@ registerModel({
                 );
                 let amount = 0;
                 for (const chatWindow of allHiddenWithThread) {
-                    if (chatWindow.thread.channel.localMessageUnreadCounter > 0) {
+                    if (chatWindow.thread.channel && chatWindow.thread.channel.localMessageUnreadCounter > 0) {
                         amount++;
                     }
                 }