Consider the following scenario:

• You establish a Terminal Services session on a Windows Server 2008-based terminal server.
• You create a virtual channel handle on the Terminal Services session by using the Citrix Virtual Channel SDK or by using the Terminal Services API.
• You keep the virtual channel handle open after you disconnect the Terminal Services session. Later, you reconnect the Terminal Services session.
• You call the WriteFile function by using the virtual channel handle.

In this scenario, the WriteFile function fails. Additionally, when you call the GetLastError function, it returns an instance of error 1 (ERROR_INVALID_FUNCTION).

This problem affects applications that use virtual channels in Terminal Services sessions.

When the virtual channel transfers from the old session to the new session, Terminal Services does not verify that the virtual channel already exists in the new session.

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 this specific problem. 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

No prerequisites are required.

Restart requirement

You must 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 item in Control Panel.

Windows Server 2008, x86-based versions

Windows Server 2008, Itanium-based versions

Windows Server 2008, x64-based versions

To work around this problem, close and then reopen the virtual channel every time that you establish a new Terminal Services session.

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

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.