

and that speculation would be that the upgrade, originally released in April, 2012, is no longer needed by any system because the version it upgraded is no longer available for download, and thusĬould only be installed on a system that old - and I'd venture a guess that there's also a dependency of the signature files on the version of MSE installed, and that the current signature files won't even work with the older version. I could only but speculate on why it's no longer available. I am finding Ms Security Essentials definitions Updates but i don't find the KB2691905 Update
