Last Tested: Jul 23, 2020
This error when trying to sign in through a SAML provider can come from attempting to authenticate when a user does not have a value set for an attribute that is required by Looker (see https://docs.looker.com/admin-options/security/saml-auth#pairing_saml_attributes_with_looker_user_attributes)
For Google Auth, required user attributes are not available, so the issue may be this instead.
Real life scenario:
Q: You are trying to merge LDAP users to looker users. (you have already created a user, gave email credentials using the API) But we are still seeing
Unsuccessful authentication. Do the first and last name need to also match from LDAP to Looker?
A: the merge only looks at the email - but a failed merge would not cause an unsuccessful authentication, it would cause two users. So there's something wrong with the LDAP settings that's preventing users from being able to authenticate
Running the test in the LDAP settings page will show more information on what's missing!
Test result will look something like
Found 'NameID': 'firstname.lastname@example.org'.
Missing value for 'Email'.
Missing value for 'FirstName'.
Missing value for 'LastName'.
Failing authentication because this user has some missing fields.