--- title: SSO Login Not Working – Authentication Error description: Is your SSO login not working? This guide explains what to check if one or more users are unable to sign in using Single Sign-On (SSO). --- [Skip to content](https://support.lemontaps.com/en/sso-login-funktioniert-nicht-was-kann-ich-tun-0#main-content) - [English](https://support.lemontaps.com/en/sso-login-funktioniert-nicht-was-kann-ich-tun-0) - [Deutsch](https://support.lemontaps.com/de/sso-login-funktioniert-nicht-was-kann-ich-tun-0) English Show submenu for translations ![Lemontaps Logo-Black (1)](https://support.lemontaps.com/hubfs/Lemontaps%20Logo-Black%20(1).svg) - Start - Produkte - Preise - Blog - Unternehmen Open main navigation Close main navigation - Start - Produkte - Preise - Blog - Unternehmen - - [English](https://support.lemontaps.com/en/sso-login-funktioniert-nicht-was-kann-ich-tun-0) - [Deutsch](https://support.lemontaps.com/de/sso-login-funktioniert-nicht-was-kann-ich-tun-0) English Show submenu for translations - [Contact us](mailto:support@lemontaps.com) [Contact us](mailto:support@lemontaps.com) How can we help you? - There are no suggestions because the search field is empty. 1. [Lemontaps Helpdesk](https://support.lemontaps.com/en?hsLang=en) 2. [Troubleshooting & Problem Resolution](https://support.lemontaps.com/en/troubleshooting-problem-resolution?hsLang=en) 3. [Login & Access Issues](https://support.lemontaps.com/en/troubleshooting-problem-resolution?hsLang=en#login-access-issues) August 19, 2026 # SSO Login Not Working – Authentication Error **Quick Guide:** If the Single Sign-On (SSO) login fails with the error message *"Authentication error: failed to obtain access token"*, the cause is usually a central SSO configuration issue or an expired client secret configured with the identity provider. ![](https://support.lemontaps.com/hs-fs/hubfs/image-png-Aug-19-2026-09-47-40-3483-AM.png?width=336&height=94&name=image-png-Aug-19-2026-09-47-40-3483-AM.png) --- ### First, check: Who is affected? Choose the appropriate scenario and go to the corresponding section: **a) Only one user is affected** → see *Problem affects a single user* **b) Multiple or all users are affected** → see *Problem affects multiple users* --- ### a) Problem affects a single user If only one user is affected while others can log in via SSO, the issue is usually not caused by the central SSO configuration. Check the following: - Does the user exists correctly in the Identity Provider - is the user assigned to the correct group or application - Is the user allowed to access via SSO If the problem persists, proceed to **"*Problem persists* below"**. --- ### b) Problem affects multiple users If multiple or all users are affected, the issue is likely with the central SSO configuration. 1. **Check login logs at the Identity Provider** Ask your IT department to review the login logs to identify specific error messages or configuration issues. 2. **Check the Client Secret** In many cases, the Client Secret has expired.  Verify: - Whether the Client Secret is still valid - If necessary, renew the Client Secret An expired Client Secret completely prevents SSO login. --- ### Problem persists? If users still cannot log in via SSO after checking or renewing the Client Secret, contact Lemontaps Support at: [support@lemontaps.com](mailto:support@lemontaps.com) Please provide: - The Identity Provider used (e.g., Entra ID) - Since when the login stopped working - Exact error message (if available) This helps us troubleshoot the issue quickly and accurately. --- ### FAQs **What happens if the Client Secret expires?** Many OIDC integrations use Client Secrets with limited validity. Once expired, SSO login is no longer possible. **We no longer have access to the account – what can we do?** In this case, you can restore access using our [SSO recovery process](https://demo.lemontaps.com/share/cm9cpau8i0001kz0d9e4czpu6/tour). There, we guide you step by step on how to store a new client secret and reactivate the login. Please follow the steps below to restore the SSO connection: 1. Open the following link: **lemontaps.com/sso-recovery** *(If you experience any issues opening the link, please try again in an incognito/private browsing window.)* 2. Enter the email address of a **Team Admin**. *(Only Team Admins can receive the recovery instructions and, if necessary, forward them internally.)* 3. 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