RPC over HTTP clients cannot connect to the Windows Server 2008 RPC over HTTP servers that have RPC load balancing enabled

Consider the following scenario in a network environment:

• You have two or more Windows Server 2008-based servers.
• You configure these servers to be remote procedure call (RPC) over HTTP servers in a server farm.
• You install and you configure the Network Load Balancing (NLB) feature on these servers.
• You enable and you configure RPC Load Balancing on these servers.
  
  Note For more information about how to do this, refer to the "More Information" section.
• When the RPC over HTTP Servers are busy booting up and the servers have not communicated with oneanother, an RPC over HTTP client sends a request to connect to the server.

In this scenario, the client cannot connect to either of the RPC over HTTP servers.

For example, Outlook clients that are configured to use RPC over HTTP cannot connect to the Microsoft Exchange Server when you configure the Microsoft Exchange Server as mentioned earlier.

This issue occurs because of an error in the RPC over HTTP Load Balancing Service on the RPC over HTTP server. When the RPC over HTTP client sends the request, both of the RPC over HTTP servers assume that they are the owners of the client session. Therefore, the connection cannot be established.

Hotfix information

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Prerequisites

To apply this hotfix, you must be running Windows Server 2008 or Windows Server 2008 Service Pack 2 (SP2):
For more information about how to obtain a Windows Server 2008 service pack, click the following article number to view the article in the Microsoft Knowledge Base:

Restart requirement

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

Hotfix replacement information

This hotfix does not replace a previously released hotfix.

File information

The global version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows Server 2008 file information notes

• The files that apply to a specific product, SR_Level (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table.
  Collapse this tableExpand this table

  Version	Product	SR_Level	Service branch
  6.0.600 1 . 22xxx	Windows Server 2008	SP1	LDR
  6.0.600 2 . 22xxx	Windows Server 2008	SP2	LDR

• Service Pack 1 is integrated into the release version of Windows Server 2008. Therefore, RTM milestone files apply only to Windows Vista. RTM milestone files have a 6.0.0000.xxxxxx version number.
• The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed separately in the "Additional file information for Windows Server 2008" section. MUM files and MANIFEST files, and the associated security catalog (.cat) files, are extremely important to maintaining the state of the updated component. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.

For all supported x86-based versions of Windows Server 2008

For all supported x64-based versions of Windows Server 2008

For all supported IA-64-based versions of Windows Server 2008

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

For more information about the RPC over HTTP proxy, visit the following Microsoft Web sites:For more information about the RPC load balancing service, visit the following Microsoft Web sites: For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:

Additional file information

Additional file information for Windows Server 2008

Additional files for all supported x86-based versions of Windows Server 2008

Additional files for all supported x64-based versions of Windows Server 2008

Additional files for all supported IA-64-based versions of Windows Server 2008