This error may appear during a Windows Vista installation, when performing a Windows Anytime Upgrade. The problem may appear if the Slsvc.exe utility (Software Licensing service) is not running while the upgrade is taking place.
Don't despair if An error occurred during the license ...
To get past this problem, close the SLCC dialog box and then reboot the computer. After the computer starts up again, make sure that Slsvc.exe is running before you attempt to carry out the upgrade again. To check on this, click the Start button, type services in the Start search box, and click Services in the Programs list. Type in your password if you are asked for it. You will see the Services control panel. Once there, you can verify that Software Licensing has been Started. Then, start your upgrade process again.
TipFor more information, please see: How to fix Update error #0x80070426