This issue occurs because Unified Access Gateway maintains a pool of objects that are used to store information about incoming requests. When a new request arrives at the Unified Access Gateway server, Unified Access Gateway takes an object from the pool and may read property values from the object. One of the properties defines whether the client application for the request can support HTML-rendered error pages such as for all web browsers, or the client application can support only HTTP error code values such as for Microsoft Outlook or Exchange ActiveSync. In some circumstances, the property is not reset correctly when an object is returned to the pool. If a new OWA request uses an object that was previously used to handle an Outlook Anywhere or Exchange ActiveSync request, Unified Access Gateway may incorrectly return an HTTP Status code to the browser because the property value is incorrect.