AADSTS20001: The sign-in response message does not contain an issued token.

Hi Dzung Vu,

The error AADSTS20001, indicating that the sign-in response message lacks an issued token, is often linked to AD FS (SSO) configuration. You can use these steps for troubleshooting:

1. Check SSO Configuration: Test SSO with a colleague under the same domain to isolate account configuration issues¹.

2. Perform Office 365 SSO Test: Use Microsoft Remote Connectivity Analyzer for an Office 365 SSO test.

3. Verify AD FS Configuration: Look for misconfigurations preventing proper token issuance.

4. Review Application Registration: Register the application on either Azure AD or ADFS, not both.

5. Inspect Configured Rules: Errors in rules can lead to failed logins without token inclusion.

Useful links for more info:
(1) [Microsoft Community](https://answers.microsoft.com/en-us/msoffice/forum/all/sign-in-error-aadsts20001-signin-response-message/a3a3b782-efec-46bd-97aa-fbb042f60f7d)
(2) [Microsoft Remote Connectivity Analyzer](https://testconnectivity.microsoft.com/)
(3) [Microsoft Learn](https://learn.microsoft.com/en-us/answers/questions/15141/ad-fs-saml-sign-on-with-azure-ad-enterprise-app-aa)