If an unlicensed client connects to a Terminal Server for the first time, the Terminal Server issues the client a temporary Terminal Server Client Access License (CAL) token. After the user has logged into the session, the Terminal Server instructs the License Server to mark the issued temporary Terminal Server CAL token as being validated. The next time the client connects, an attempt is made to upgrade the validated temporary Terminal Server CAL token to a full Terminal Server CAL token. If no license tokens are available, the temporary Terminal Server CAL token will continue to function for 90 days. The license is stored in the client's registry.
Thirty-two bit RDP clients store their license under the key
This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
How to back up and restore the registry in Windows
To have us fix this problem for you, go to the "Fix it for me
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To fix this problem automatically, click the Fix it
button or link. In the File Download
dialog box, click Run
, and then follow the steps in the Fix it Wizard.
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- This wizard may be in English only. However, the automatic fix also works for other language versions of Windows.
- If you are not on the computer that has the problem, save the Fix it solution to a flash drive or a CD and then run it on the computer that has the problem.
Then, go to the "Did this fix the problem?
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To clean the client's license cache, just delete this key and its
subkeys. The next time the client connects to the server, it
will obtain another license.
For 16-bit RDP clients, run regedit /v. Then delete the keys under
"\Software\Microsoft\MSLicensing" to clean the client's license cache.
You can also delete the BIN files from \Windows\System\Regdata.
The RDP client for Macintosh stores the license in a file on the local computer in the folder hierarchy under /users/Shared/Microsoft/RDC Crucial Server Information/. To clean the Macintosh client's license cache, delete the contents of this folder. The client will try to obtain a new license from the server the next time that it connects.
If you delete the
subkey on a client that is running Windows Vista or a later version, later attempts to connect to a Terminal Server may fail. Also, you receive the following error message:
An Error occurred in the Licensing Protocol
To resolve this problem, right-click the Remote Desktop Connection
shortcut, and then click Run as Administrator
. By default, the remote desktop connection runs as a user with the lowest user permissions. By default, a restricted user does not have permission to write registry entries to HKEY_LOCAL_MACHINE. Therefore, attempts to rewrite the MSLicensing key fail. Starting Remote Desktop Connection with administrative credentials provides the permissions that are necessary to write the needed registry keys.
Did this fix the problem?
- Check whether the problem is fixed. If the problem is fixed, you are finished with this section. If the problem is not fixed, you can contact support
- We would appreciate your feedback. To provide feedback or to report any issues with this solution, please leave a comment on the "Fix it for me
" blog or send us an email
Article ID: 187614 - Last Review: July 19, 2013 - Revision: 8.0
- Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
- Microsoft Windows Server 2003, Enterprise x64 Edition
- Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
- Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems
- Microsoft Windows Server 2003, Datacenter x64 Edition
- Microsoft Windows Server 2003, Enterprise Edition (32-bit x86)
- Microsoft Windows Server 2003, Standard Edition (32-bit x86)
- Microsoft Windows Server 2003, Standard x64 Edition
- Windows Vista Business
- Windows Vista Enterprise
- Windows Vista Home Basic
- Windows Vista Home Premium
- Windows Vista Starter
- Windows Vista Ultimate
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