Single sign-on (SSO) authentication is disabled for an application configuration that uses the Autodiscover service in Microsoft Forefront Unified Access Gateway (UAG) 2010.
Trunk authentication is enabled on the relevant trunk.
Service Pack 2 for Microsoft Forefront Unified Access Gateway (UAG) 2010 is installed.
In this scenario, Autodiscover requests may be unsuccessful, and the following error message is returned to the client:
500 - Internal Server error
When this problem occurs, external clients cannot use Autodiscover to set up new profiles. Additionally, existing clients may be repeatedly prompted to confirm that they trust the Autodiscover fully qualified domain name (FQDN) for configuring their settings.
To confirm that you are experiencing this problem, use a web browser to access the Autodiscover FQDN from an external client. For example, browse to a URL that resembles the following: