diff --git a/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml b/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml
index 6f016708cfd..ad304bf8779 100644
--- a/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml
+++ b/addons/mail/static/src/discuss/core/web/discuss_sidebar_categories.xml
@@ -34,7 +34,7 @@
                 <t t-set="thread" t-value="thread"/>
             </t>
         </t>
-        <t t-elif="store.discuss.thread.in(category.threads)" t-call="mail.DiscussSidebarChannel">
+        <t t-elif="store.discuss.thread?.in(category.threads)" t-call="mail.DiscussSidebarChannel">
             <t t-set="thread" t-value="store.discuss.thread"/>
         </t>
     </t>
diff --git a/addons/mail/static/tests/discuss/core/web/discuss_tests.js b/addons/mail/static/tests/discuss/core/web/discuss_tests.js
index 857ff05c9f6..cc7540cd7d0 100644
--- a/addons/mail/static/tests/discuss/core/web/discuss_tests.js
+++ b/addons/mail/static/tests/discuss/core/web/discuss_tests.js
@@ -199,4 +199,7 @@ QUnit.test("no conversation selected when opening non-existing channel in discus
     const { openDiscuss } = await start();
     await openDiscuss(200); // non-existing id
     await contains("h4", { text: "No conversation selected." });
+    await contains(".o-mail-DiscussSidebarCategory-channel .oi-chevron-down");
+    await click(".o-mail-DiscussSidebar .btn", { text: "Channels" }); // check no crash
+    await contains(".o-mail-DiscussSidebarCategory-channel .oi-chevron-right");
 });