"Failed Silent Auth" and "Login Required" Errors

[lihua.zhang]

Overview

This article explains the “Failed Silent Auth” error with a login_required description that can appear in tenant logs. This error indicates that a silent authentication request could not be completed because there was no active user session.

Applies To

• Silent Authentication
• Single-Page Applications (SPA)
• Universal Login

Cause

The login_required error during a silent authentication attempt signifies that Auth0 could not find an active login session for the user. This is expected behavior under several conditions:

• No Active Session: The user has not logged in previously, or their session has expired. The duration of the login session is configured in the Tenant Settings > Advanced > Log In Session Management.
• Third-Party Cookie Issues: Silent authentication relies on a cookie set for the Auth0 domain. If the application is running on a different domain and not using a custom domain, modern browsers may block this third-party cookie, preventing Auth0 from finding the session.
• Application Misconfiguration: The application logic may not be correctly handling the login_required error. An incorrect implementation can cause the application to repeatedly and unsuccessfully attempt a silent authentication, leading to a large volume of “Failed Silent Auth” logs.

Solution

The login_required error is a standard part of the authentication flow that indicates an interactive login is needed. The client application must be configured to handle this response correctly.

1. Handle the login_required Error: When a silent authentication call fails with a login_required error, the application should catch this specific error and redirect the user to the interactive Universal Login page. This allows the user to enter their credentials and establish a new session.
2. Use a Custom Domain: To avoid issues with third-party cookie blocking, it is highly recommended to configure a custom domain for the Auth0 tenant. This ensures that the application and the Auth0 authentication cookies are on the same domain, preventing them from being blocked by the browser.
3. Check Session Lifetime: Review the Require log in after setting in Tenant Settings > Advanced > Log In Session Management to ensure the session duration is appropriate for the application’s security requirements and user experience needs.
   
   
   
   By implementing proper error handling, the application will redirect users to log in when necessary, preventing a loop of failed silent authentication attempts and excessive log entries.