Unexpected Error, please contact support SAML auth

I have configured SAML Single Signon with Active Directory ADFS following the instruction here SAML Single Signon with Active Directory ADFS. When a user logs in they get an error Unexpected Error, please contact support. What could be wrong? I have a Docker install version 1.8.9. Where do I check for logs (path?). Thank you.

Logs will be in the database. You’ll need to disable SAML, log in and look at them.

The most likely cause is a syntax error in your settings-custom.php file.

Thanks for the quick response. I am getting this error below
SAML SSO failed: invalid_response. Last Reason: The status code of the Response was not Success, was Requester -> urn:oasis:names:tc:SAML:2.0:status:InvalidNameIDPolicy Exception Type: OneLogin_Saml2_Erro

I figured it out. Thank you.