Can't access a CAS website such as OWA/ECP/Autodiscover in Exchange Server 2016

Applies to: Exchange Server 2016 Enterprise EditionExchange Server 2016 Standard Edition

Symptoms


In a Microsoft Exchange Server 2016 environment, assume that the Active Directory forest root domain is configured as a single label domain that has one or two characters, such as ab. When a user or administrator tries to access a website (for example, Outlook Web App (OWA), Exchange Control Panel (ECP), Autodiscover and so on) through the Client Access services (CAS), an unhandled exception occurs.

Cause


This issue occurs because the single label domain isn't correctly handled in forest name validation.

Resolution


To fix this issue, install Cumulative Update 9 for Exchange Server 2016 or a later cumulative update for Exchange Server 2016.

Status


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

References


Learn about the terminology that Microsoft uses to describe software updates.