Thanks to Evil Avatar for the heads up on this one.
We"re hearing from a small number of customers (less than 1%) that are having issues with the Fall Console Update. I"ve been told that the team should have an updated version in the next 12-24 hours. We"ll let you know when the issue is resolved.
If you are having problems with the update for any reason, please call Xbox Support (1-800-4-MY-XBOX in the US and Canada). We"re working with those affected to get them back up and running, and we"re committed to making sure the update doesn"t cause problems for anyone else.