diff --git a/web_src/js/features/admin/common.js b/web_src/js/features/admin/common.js
index b6b192a29..250608069 100644
--- a/web_src/js/features/admin/common.js
+++ b/web_src/js/features/admin/common.js
@@ -10,7 +10,6 @@ export function initAdminCommon() {
   }
 
   // check whether appUrl(ROOT_URL) is correct, if not, show an error message
-  // only admin pages need this check because most templates are using relative URLs now
   checkAppUrl();
 
   // New user
diff --git a/web_src/js/features/common-global.js b/web_src/js/features/common-global.js
index 8ee5ce25b..474993045 100644
--- a/web_src/js/features/common-global.js
+++ b/web_src/js/features/common-global.js
@@ -461,5 +461,5 @@ export function checkAppUrl() {
     return;
   }
   showGlobalErrorMessage(`Your ROOT_URL in app.ini is "${appUrl}", it's unlikely matching the site you are visiting.
-Mismatched ROOT_URL config causes wrong URL links for web UI/mail content/webhook notification.`);
+Mismatched ROOT_URL config causes wrong URL links for web UI/mail content/webhook notification/OAuth2 sign-in.`);
 }
diff --git a/web_src/js/features/user-auth.js b/web_src/js/features/user-auth.js
index e3ce4e56e..af380dcfc 100644
--- a/web_src/js/features/user-auth.js
+++ b/web_src/js/features/user-auth.js
@@ -1,10 +1,13 @@
 import $ from 'jquery';
+import {checkAppUrl} from './common-global.js';
 
 export function initUserAuthOauth2() {
   const outer = document.getElementById('oauth2-login-navigator');
   if (!outer) return;
   const inner = document.getElementById('oauth2-login-navigator-inner');
 
+  checkAppUrl();
+
   for (const link of outer.querySelectorAll('.oauth-login-link')) {
     link.addEventListener('click', () => {
       inner.classList.add('gt-invisible');