.net 3.5 and server 2012, server 2012 R2, Windows 8, and Windows 8.1

As most of you know by now, you need to specify the media location when installing .net 3.5 – well I did that today as I always do and it kept failing and telling me “The source files could not be found”. Eventually I came across a few other blog posts that said the following updates that came out on August 12, 2014 if installed will cause this installation to fail:

  • KB2966826
  • KB2966827
  • KB2966828

Sure enough, I had kb2966827 installed so I uninstalled it and the .net 3.5 installation succeeded. I am re-posting this fix in hopes that others will come across it. There are only a few blog posts out there and I haven’t found any official posts from Microsoft yet.

It does appear that

2966827 and 2966828 were revised on 9.9.2014  and 2966727 was revised again today (9.16.2014) so Microsoft might be in the process of fixing this issue.

For more details see the following:

Another blog post outlining the issue + more details

MS Article on released and revised updates


*UPDATE* (10.27.2014)

October patches came with kb3005628, who’s sole purpose is to remove kb2966827 and kb2966828. A simpler fix is to just manually remove them…



  1. REMOVE KB2966827!!!
    THANK YOU!!! I cannot believe how much time I wasted on this. Someone from Microsoft should be taken out an summarily executed.

  2. Glad I could help! If it makes you feel any better I wasted half a day on this. I thought I was losing it.

  3. uninstall 2966828 before trying to enable net 3.5. Did not work . did not have the 2966826 or 2966827. windows 8.1 pro 64

  4. I can not uninstall KB2966826. In the control panel, when I select KB2966826, disappears the uninstall button. If I try to uninstall KB2966826 from the command prompt as an administrator, the system responds by saying that the security updates can not be uninstalled. Could you help me?

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