Found a download for Windows 8.1 KB3121255 update on the Microsoft web site.
link
From what I can read from your original link, this should have been installed via a normal windows update.
I'm a big fan of the notion that if it's not broken, it doesn't need fixing. You didn't mention if you were experiencing the system crash described in the original link that you provided.
If you want to try to get this patch, run Windows Update and see if it applies it. If it fails to apply the patch, you could then try downloading and installing the patch yourself, using the link in this post.