Issue: When users log in to Salesforce and succeed all configured methods of Advanced Authentication, an error message Single Sign-on error is displayed. This is due to an invalid SAML assertion configured in the Single Sign-On Settings of the Salesforce console.
Workaround: Perform the following steps:
Navigate to Settings > Identity > Single Sign-On Settings in the Salesforce console.
Set SAML Identity Type to Assertion contains the User’s Salesforce username.
Specify IDPEmail in Attribute Name.
Click Save.