Cumulative Update for Windows 10 Version 1607 for x64-based Systems (KB3189866)
So the latest MS Windows 10 cumulative update download (and its a big one) is reported getting stuck around the 40% mark. You can have your PC running for hours and the update won't download any more.
Now there has been a lot of complaints on the MS site and elsewhere but as yet still no response from MS (of course). The problem is that to fix this MS would have to issue a patch, but how will that get installed when your update is already stuck downloading this update.
One way around this has been suggested that you go to the Windows Update Catalog website and search for the update and download it from there. But to do so you'll need to install the antiquated ActiveX control. You could also search for the updates via a RSS feed. There is another way where you need to manually stop the update service, delete cached files, restart the service and try again - and hope it works.
But you can download the updates directly from the MS servers for both 32 bit and 64 bit systems. Once you download the .msu file you can run it and it will install the update. Then re-boot and check for updates again to install any other updates that weren't installed.
The article for this can be found at Softpedia News and the link to each of the updates is below. From the article:
Here are the download links should you want to give a try to manual downloading – these links point to the updates stored on Microsoft’s servers, so they’re fully secure and do not pose a threat to your PC.
KB3189866 x64 (431MB)
KB3189866 x86 (255MB)
I've posted this here as there has been a lot of complaints about this update and few responses as to how to effectively fix this with minimal fuss. Feel free to further disseminate this info to help out others with this problem.