SAML Unknown Error from Provider "The SAML response is not valid. Response do not contain signature"

Last Updated: Sep 10, 2025

Overview

The customer is experiencing failed SAML login attempts with the error message: "Exception": "SGT5.Common.Utilities.Exceptions.MyException: The SAML response is not valid. Response do not contain signature.
at SGT5.Web.Saml.SamlResponse.Validate().

The SAML Response also contains the following:

    <samlp:Status>
        <samlp:StatusCode Value="urn:oasis:names:tc:SAML:2.0:status:Responder"/>
        <samlp:StatusMessage Value="Unknown error from provider"/>
    </samlp:Status>

Applies To

SAML

Cause

The customer had a misconfiguration on the IdP side by setting the ACS URL to https://{auth0_domain}/samlp/{client_id} covered here: https://auth0.com/docs/api/authentication?javascript#accept-request

Solution

By changing the ACS URL on the IdP side to https://{auth0_domain}/login/callback, they were able to log in successfully.