Can't access EWS from Outlook/OWA add-ins via makeEwsRequestAsync in Exchange Server 2016 and Exchange Server 2013

Applies to: Exchange Server 2016 Enterprise EditionExchange Server 2016 Standard EditionExchange Server 2013 Enterprise More

Symptoms


Assume that accessing external Exchange Web Services (EWS) URL is blocked from internal Exchange servers in a Microsoft Exchange Server 2016 or Exchange Server 2013 environment. In this situation, the client applications that are posting ExecuteEwsProxy calls will be failed to connect, such as Salesforce add-in for Outlook and Outlook Web App (OWA).

Cause


This issue occurs because the ExecuteEwsProxy function is only using external EWS URL. This causes the makeEwsRequestAsync method fail to call EWS.

Resolution


For Exchange Server 2016, install Cumulative Update 8 or a later cumulative update for Exchange Server 2016.

For Exchange Server 2013, install Cumulative Update 19 or a later cumulative update for Exchange Server 2013.

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.