Microsoft KB Archive/811803

= &quot;Remote Assistance Failed &quot;Error Message After You Switch to Terminal Server Mode =

Article ID: 811803

Article Last Modified on 2/28/2007

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APPLIES TO


 * Microsoft Windows Server 2003, 64-Bit Datacenter Edition
 * Microsoft Windows Server 2003, Enterprise x64 Edition
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Web Edition

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SYMPTOMS
When you switch from Remote Administration mode to Terminal Server mode, you may not be able to use the Remote Assistance feature. When you use a Remote Assistance request to invite someone to help you, the assistant may not be able to connect to your computer. Then, the assistant receives the following error message:

Remote Assistance failed



CAUSE
This issue may occur in the following scenario:
 * 1) A server running Terminal Server Licensing is unavailable when Terminal Server issues the Remote Assistance request.
 * 2) The Remote Assistance request is used after Terminal Server contacts a server running Terminal Server Licensing.

The server running Terminal Server Licensing may be initially unavailable when you switch from Remote Administration mode to Terminal Server mode.



RESOLUTION
To resolve the issue, restart the Terminal Server, and then re-create the Remote Assistance request.



STATUS
Microsoft has confirmed that this is a bug in the Microsoft products that are listed at the beginning of this article.



MORE INFORMATION
Terminal Server uses a License Server to issue a Terminal Services client license when you create a Remote Assistance request. Terminal Server requests an X509 certificate from the License Server and uses it with the Microsoft Remote Desktop Protocol (RDP) to encrypt communication between Terminal Server and the Terminal Server client.

If a server running Terminal Server Licensing is unavailable, Terminal Server uses a less secure method. This method uses a public key to create a Remote Assistance request. Terminal Server continues to try to register with a server running Terminal Server Licensing until such a server is contacted.

When Terminal Server contacts a server running Terminal Server Licensing, all existing Remote Assistance requests that were created by using the public key become invalid. Therefore, when you try to use the Remote Assistance request that was created before Terminal Server has contacted the License Server, you may receive the &quot;Remote Assistance failed&quot; error message.

For example, this issue may occur in the following scenario:
 * 1) You switch from Remote Administration mode to Terminal Server mode and then restart the computer.
 * 2) You create a Remote Assistance request before the computer has identified a server running Terminal Server Licensing. Terminal Server issues the Remote Assistance request by using the less secure method (the public key instead of the X509 certificate).
 * 3) Terminal Server finds a License Server, and any subsequent Remote Assistance requests are created with the X509 certificate.
 * 4) The assistant tries to use the Remote Assistance request (that was created without the X509 certificate) to connect to Terminal Server.
 * 5) The assistant receives the “Remote Assistance failed” error message, because the Remote Assistance request that was created with the public key is invalid.

Keywords: kberrmsg kbbug KB811803

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