Event ID - 26

Event Id26
SourceMicrosoft-Windows-TerminalServices-Licensing
DescriptionAll available "%1!s!" Terminal Services client access licenses (TS CALs) for product "%2!s!" on Terminal Services license server "%3!s!" have been removed. Use TS Licensing Manager to re-register the TS CALs.
Event InformationAccording to Microsoft :
Cause :
This event is logged whenTerminal Services client access licenses (TS CALs) for product on Terminal Services license server have been removed.
Resolution :
Reinstall the TS CALs onto the license server by using the telephone method

To resolve this issue, reinstall the Terminal Services client access licenses (TS CALs) onto the Terminal Services license server by using the telephone method. When you call the Microsoft Clearinghouse, ensure that your License Purchase Agreement information is readily available.
To perform this procedure, you must have membership in the local Administrators group, or you must have been delegated the appropriate authority.
To reinstall TS CALs by using the telephone method:
  1. On the license server, open TS Licensing Manager. To open TS Licensing Manager, click Start, point to Administrative Tools, point to Terminal Services, and then click TS Licensing Manager.
  2. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
  3. In the left pane, click All Servers, click the name of the license server, and then on the View menu, click Properties.
  4. On the Connection Method tab, in the Connection method list, select Telephone.
  5. In the Select Country or Region list, select the appropriate country/region.
  6. Click OK to close the Properties dialog box.
  7. Right-click the license server and then click Install Licenses.
  8. Click Next.
  9. On the Obtain client license key pack page, use the telephone number that is displayed to call the Microsoft Clearinghouse, and give the representative your Terminal Services license server ID and the required information for the licensing program through which you purchased your TS CALs. The representative then processes your request to install TS CALs, and gives you a unique ID for the TS CALs. This unique ID is referred to as the license key pack ID.
    Important : Retain a copy of the license key pack ID. Having this information with you will facilitate communications with the Microsoft Clearinghouse should you need assistance with recovering TS CALs.
  10. In the Install Licenses Wizard, on the Obtain client license key pack page, enter the license key pack ID provided by the representative into the boxes provided, and then click Next. The TS CALs are installed onto the license server.
  11. To complete the process, click Finish. The license server can now issue TS CALs to clients that connect to a terminal server.
Verify :
To verify that Terminal Services client access licenses (TS CALs) are installed and available on the Terminal Services license server, use the TS Licensing Manager tool.
To perform this procedure, you must have membership in the local Administrators group, or you must have been delegated the appropriate authority.
To verify that TS CALs are installed and available:
  1. On the license server, open TS Licensing Manager. To open TS Licensing Manager, click Start, point to Administrative Tools, point to Terminal Services, and then click TS Licensing Manager.
  2. If the User Account Control dialog box appears, confirm that the action it displays is what you want, and then click Continue.
  3. In the left pane, expand All Servers, and then click the license server. In the right pane, the type, version, and number of TS CALs installed on the license server is listed.
Note : To verify that the terminal server can discover (contact) a Terminal Services license server with the appropriate type of Terminal Services client access licenses (TS CALs), use Licensing Diagnosis in the Terminal Services Configuration tool on the terminal server.
Reference LinksEvent ID 26 from Source Microsoft-Windows-TerminalServices-Licensing

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