This can be mitigated by keeping the system current with updates (security updates are released for all versions), but the Windows Catalog, does not archive updates forever.

Feature updates are only supported for 18 months, I have found any installation on an unsupported build, actually has problems getting updates. The only way I have found to upgrade older Windows 10 installations that are NOT on a build that is currently supported (1507,1511,1607,1703,1709) is to upgrade to each of those versions before attempting to upgrade to (1803,1809, and 1903). I want to update my windows to the latest version. is there anything I am missing here, or there is something else that I need to. So unless you watched the entire process you would miss what was happening (which is exactly what I was not doing). The machine would go through the process, reboot several times, and then suddenly start to roll the changes back. When Windows Update attempted to install the feature update it would fail silently. This error message was only being displayed when I attempted to either use the current Upgrade Assistant and/or the Media Creation Tool. I decided that it was time to update this machine, I spent the better part of a day attempting various methods to upgrade it one of the more recent Windows 10 versions, but each time I would receive an error. In my case, the installation was an Insider Preview build based on my notes, that was later upgraded to the final build (RTM) 10240 at some point. In my case, the installation was actually a virtual machine. I have given it fixed 2MB Internet, and I keep it running until it restarts itself. It hasn't been able to completely update my windows version and this update still shows, sometimes downloading, and sometimes installing, but can do nothing else. The problem is that it has been three days that my system downloads this update, try to install it, but then start downloading again and start installing again.

But there was this update 'Windows feature update 1803', it was downloading.

Windows version 1511 update