Outlook Web Access Error Message "Internal Server Error" with Certain Firewalls (267910)

The information in this article applies to:

Microsoft Exchange Server 2003 Enterprise Edition
Microsoft Exchange Server 2003 Standard Edition
Microsoft Exchange 2000 Server

This article was previously published under Q267910

SYMPTOMS

When you use Microsoft Internet Explorer 5 or later to gain access to Microsoft Outlook Web Access (OWA), you may receive the following error message:

Internal server error

However, OWA works when you use a virtual private network (VPN) or a local intranet. Earlier version browsers also work.

CAUSE

This issue can occur because the Hypertext Transfer Protocol (HTTP) 1.1 is used when you use Internet Explorer 5 and later to gain access to OWA, and the HTTP 1.1 protocol is not supported by all firewalls. If the HTTP 1.1 protocol is not supported by the firewall, certain packets from the client are blocked and you receive the error message in the "Symptoms" section of this article.

RESOLUTION

To resolve this issue, implement a firewall solution that supports HTTP 1.1 packets.

WORKAROUND

To work around this issue, do one of the following:

Implement a SSL connection so that no requests are filtered.
Modify the firewall so that the firewall passes all HTTP packets regardless of the protocol
Use an earlier version browser.

MORE INFORMATION

For additional information, click the article numbers below to view the articles in the Microsoft Knowledge Base:

253615 XWEB: Using Browsers Earlier Than Internet Explorer 5 to Gain Access to Outlook Web Access

249557 XWEB: No Option to Gain Access to OWA with Internet Explorer 5 Using Code Path for Earlier Version Browsers

Modification Type:	Minor	Last Reviewed:	4/25/2005
Keywords:	kberrmsg kbprb KB267910