3789865 - Error "Duplicate emails for user authentication" when logging in to XSA service via SAML/ADFS

When attempting to log in to an SAP HANA XS Advanced (XSA) service using SAML authentication with an external identity provider (such as ADFS), the login fails with an internal server error. The URL contains the parameter:

  error=access_denied&error_description=Duplicate+emails+for+user+authentication

The XSUAA audit log records the following error for example:

  SAMLAuthenticationError: Incorrect result size: expected 1, actual 3

• SAP HANA Extended Application Services, Advanced Model

duplicate emails, ADFS, SAML, XSA, XSUAA, access denied, Duplicate+emails+for+user+authentication, shadow user, SAMLAuthenticationError, Incorrect result size, login error, HANA XS Advanced, identity provider, NameID, case sensitivity, UAA users table, BC-XS-SEC, HANA platform 2.0 , KBA , BC-XS-SEC , UAA and Security for HANA XSA engine , BC-XS-RT , XS Advanced Runtime / XS Controller , Problem