SymptomsWhen end users attempt to access the Forefront UAG portal, they may receive the following message "An authentication error occurred when signing in." There may also be an event 151 in the event viewer or in the Web Monitor with the description "WS-FAM: User with lead user claim value [user_name] could not be signed in. Session ID: [session_ID], Trunk name: [trunk_name]."

CauseAn unknown error occurred when the user attempted to sign in.

SolutionThe user should attempt to sign in to the Forefront UAG portal again. If they continue to receive this error, you should collect traces from the InternalSite and troubleshoot any problems that occur in InternalSite. For information about collecting traces, download the Forefront UAG Tracing Symbols ( and follow the instructions in the guide.