diff --git a/main/auth/external_login/login.ldap.php b/main/auth/external_login/login.ldap.php
index 7b1d77f2c8..873c2d6e94 100644
--- a/main/auth/external_login/login.ldap.php
+++ b/main/auth/external_login/login.ldap.php
@@ -71,5 +71,7 @@ if ($ldap_user !== false) {
     error_log('extldap_authenticate error');
     $loginFailed = true;
     $uidReset = false;
-    unset($_user['user_id']);
+    if (isset($_user) && isset($_user['user_id'])) {
+        unset($_user['user_id']);
+    }
 }