diff --git a/web_src/js/features/admin/common.js b/web_src/js/features/admin/common.js
index 9b7b81db04..c2f3cde821 100644
--- a/web_src/js/features/admin/common.js
+++ b/web_src/js/features/admin/common.js
@@ -98,11 +98,12 @@ export function initAdminCommon() {
 
     if (document.getElementById('oauth2_use_custom_url')?.checked) {
       for (const custom of ['token_url', 'auth_url', 'profile_url', 'email_url', 'tenant']) {
-        if (applyDefaultValues) {
-          document.getElementById(`oauth2_${custom}`).value = document.getElementById(`${provider}_${custom}`).value;
-        }
         const customInput = document.getElementById(`${provider}_${custom}`);
-        if (customInput && customInput.getAttribute('data-available')) {
+        if (!customInput) continue;
+        if (applyDefaultValues) {
+          document.getElementById(`oauth2_${custom}`).value = customInput.value;
+        }
+        if (customInput.getAttribute('data-available')) {
           for (const input of document.querySelectorAll(`.oauth2_${custom} input`)) {
             input.setAttribute('required', 'required');
           }