RPC calls to the NNTP Service fail on a Windows Server 2003 SP1-based computer, and you notice the following error information: "System.Runtime.InteropServices.COMException (0x80004005)" (893617)

SYMPTOMS

Consider the following scenario:

On a Microsoft Windows Server 2003 Service Pack 1 (SP1)-based computer, you are running the NNTP Service.
To synchronize Network News Transport Protocol (NNTP) information among multiple servers, you make programmatic remote procedure calls (RPCs) to the NNTP Service and to the Distributed Transaction Coordinator service.

In this scenario, you experience intermittent RPC failures in your program. Additionally, when you troubleshoot your program, you notice error information that is similar to the following:

System.Runtime.InteropServices.COMException (0x80004005): DTC transaction could not be created due to missing transaction manager: Unspecified error.

CAUSE

This problem occurs because of a code problem in the Nntpapi.dll file. This file contains an incorrect Service Principal Name (SPN).

The Nntpapi.dll file that is included in Windows Server 2003 SP1 adds an additional security control over RPC calls. As client-side code, the Nntpapi.dll process calls the RpcBindingSetAuthInfoEx function when it authenticates the NNTP Service from the client. However, the Nntpapi.dll process passes an incorrect SPN in this function. Specifically, the Nntpapi.dll process passes an SPN of "NNTPSVC." Therefore, the following behavior occurs:

When a client makes an RPC connection to the NNTP Service (NNTPSVC) and calls the RpcBindingSetAuthinfoW function, the Nntpapi.dll process passes an incorrect SPN. In this situation, the RPC call still works. However, because the SPN is invalid, the RPC runtime does not verify server authentication for the client.
When the same client makes an RPC call to another server, the RPC runtime must verify whether the same context exists. If the second RPC call also passes an SPN, the RPC runtime performs a string comparison to determine whether this same context exists. In this situation, it is not important whether the SPN is valid. Both the first RPC call and the second RPC call work.
If the client makes a third RPC connection, and if the client sets a SID in the RpcBidingSetAuthInfoW function, the RPC runtime compares the SID with the SPN to determine whether this context exists. If the SPN is invalid in this situation, verification fails. Therefore, this third RPC call fails.

RESOLUTION

Hotfix information

A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Only apply it to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Microsoft Windows Server 2003 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites

No prerequisites are required to apply this hotfix.

Restart requirement

You do not have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.Microsoft Windows Server 2003, x86-based 32-bit versions

File name	File version	File size	Date	Time	Platform
Nntpapi.dll	6.0.3790.2587	14,336	08-Dec-2005	20:16	x86

Microsoft Windows Server 2003, x64-based 64-bit versions

File name	File version	File size	Date	Time	Platform	SP requirement	Service branch
Nntpapi.dll	6.0.3790.2587	17,920	08-Dec-2005	20:36	x64	SP1	SP1QFE
Wnntpapi.dll	6.0.3790.2587	14,336	08-Dec-2005	20:36	x86	SP1	WOW

Microsoft Windows Server 2003, IA64-based 64-bit versions

File name	File version	File size	Date	Time	Platform	SP requirement	Service branch
Nntpapi.dll	6.0.3790.2587	34,816	08-Dec-2005	20:36	IA-64	SP1	SP1QFE
Wnntpapi.dll	6.0.3790.2587	14,336	08-Dec-2005	20:36	x86	SP1	WOW

MORE INFORMATION

For more information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates