When you try to install WSUS to a Windows Server 2008 by adding a WSUS role you might receive the following error message:
The update could not be found. Either the update is not applicable to this computer or the update no longer exists….
To solve this error please do the following:
Open registry editor (regedit.exe)
Find the following key:
HKLM\Software\Policies\Microsoft\Windows
Locate the WindowsUpdate key and delete it.
Restart the Windows Update service
Try to install WSUS again.