This is a particularly vexing problem I ran into a while ago, while trying to use Windows Update on Windows 8.1 to get the upgrade to Windows 10. For me, Windows Update had been broken for a while and nothing I did would make it work, I kept getting unhelpful error codes such as 80244019, and Google was no help. Here’s my solution to the problem, I hope it’ll be useful to others:

* Go into Change PC Settings (from the little Windows 8 side-bar thing you get from putting your mouse in the top-right corner; I don’t know what it’s called).
* Update and Recovery
* Choose how updates get installed
* UNCHECK the option to get updates for other Microsoft products

Now run Windows Update again and with any luck, it should work! For me, it downloaded a few tiny updates, then I had to reboot, then running wuauclt.exe /updatenow triggered it to start downloading the update to Windows 10.

I’ve heard from others that the opposite solved the problem for them — checking the previously-unchecked option to allow updates for other Microsoft products. I’m not sure how or why this was preventing the Windows 10 update from working, or if Microsoft have since fixed this problem, but I’m leaving this post here in the hopes that it may be useful for others with the problem.