Troubleshooting Tip: user.saml.FORTISASE_SWG_SAML_SERVER.user-name='username' was not found in the SAML Assertion Response

Accessing SWG would fail with an authentication failed error.

Validate the Proxy SSO config. In this illustration claim Username is configured with the value username on FortiSASE.

The attribute value should be as configured on the IDP end under attribute mapping. Attributes are case-sensitive and must match both SP and IdP sides. In the IDP end attribute was set with the value 'email'. Changing the attribute value from username to email on the FortiSASE end would resolve the issue.