Unable to log in to a portal with an SAML enterprise username

Description

After adding a user from a Security Assertion Markup Language (SAML) identity provider (IDP) to a portal, logging in to the portal with the username fails. The error message, 'Unable to sign you in to ArcGIS Enterprise' is returned.

Cause

When a member is added to a portal, the username matches the existing enterprise user and format defined in the Active Directory Federation Services (AD FS).

If the username in the AD FS is in the format <User.Name>, then logging in with the format <user.name> results in a login failure.

Solution or Workaround

Log in with the username in the same format as the NameID attribute created in the AD FS, as it is case sensitive.