Yesterday, Microsoft released Windows 10 build 14393.222 to production, following its release to the Release Preview ring a couple days before. It seems, though, that the build isn't playing too nicely with a lot of people's systems.
— Glyn Press (@GlynPress) September 28, 2016
When the update fails, it will attempt to revert the changes it has made so far. In some instances, this process may also fail and result in an infinite loop. In other cases, attempting the update several times (sometimes more than 10) will allow the update to finally succeed and it will install as expected. This problem affects a large number of users and has been classified as "widespread," however, not all users are affected.
Microsoft has been working with some users on obtaining logs for the issue, however, no confirmation of an upcoming workaround or fix has been announced yet. This issue, however, does again raise the question of "what's the point of the Insider Program if Microsoft doesn't listen?" - a question that has been asked numerous times before when issues have gone unresolved, despite going through the various testing rings.