Apparently the Media Creation Tool for Windows 10 Version 1511 and updates on Windows Update were pulled because the initial upgrade build was inadvertently reversing four privacy settings on some users systems



From SuperSite for Windows:

Microsoft has revealed exactly why they pulled all the updates that were published for Windows 10 nearly two weeks ago and the related tools for installing the November Update.

Over the course of the last four days several reasons have been speculated about including Bitlocker bugs and the unauthorized activation of non-genuine systems during the upgrade/install process.

The removal of the upgrade was swift Friday night and without any communication from Microsoft to explain why it happened which of course helps to feed the speculation.

  Microsoft returns Windows 10 Media Creation Tool to the public