Consider the following scenario in Microsoft Forefront Unified Access Gateway (UAG) 2010:
You have a Forefront UAG trunk portal that is configured to perform trunk authentication to an Active Directory or other non-Active Directory Federation Services (AD FS) repository.
You publish an AD FS server by using the built-in (AD FS) 2.0 template.
You configure an application for single sign-on from the trunk repository.
In this scenario, you may find that single sign-on does not occur, and you have to authenticate again to the AD FS server.
This problem may occur because of any of the following:
You upgrade a working configuration to UAG Service Pack 2 or Service Pack 3 in some cases.
You add a new trunk that uses the AD FS repository that is linked to the published AD FS server for trunk authentication.
You make any change to the AD FS application properties.
To resolve this problem, install Service Pack 4 for Microsoft Forefront Unified Access Gateway 2010.
To work around this problem in some cases, remove and republish the AD FS server.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
See the terminology Microsoft uses to describe software updates.