Windows – Unable to install .net 3.5 on Windows server 2012

.net-3.5netwindowswindows-server-2012

I am trying to install .Net 3.5 on Windows Server 2012 and it constantly keeps failing. I am using "Add or Remove Features" and my Internet is already there. I've read that if alternate source couldn't be found, the installer tries to download online and installs it from there. However, it's not working. This is the screenshot that I keep seeing:

enter image description here

Please suggest what am I missing?

Edit:

I already tried using dism.exe /online /enable-feature /featurename:NetFX3 /Source:D:\sources\sxs /all but I do not have the source disk with me. I want to download it online.

Best Answer

This behavior can also be caused by a system administrator who configures the computer to use Windows Server Update Services (WSUS) instead of the Microsoft Windows Update server for servicing.

http://support.microsoft.com/kb/2734782

This worked for me. Windows has to download the 3.5 installation files, but the server is configured not to use Windows Update (common for managed servers), but WSUS. The above article describes how to fix this. In a nutshell:

  1. Start the Local Group Policy Editor or Group Policy Management Console (WIN+R and type gpedit.msc).
  2. Expand Computer Configuration, expand Administrative Templates, and then select System.
  3. Open the Specify settings for optional component installation and component repair Group Policy setting, and then select Enabled.

  4. Select the Contact Windows Update directly to download repair content instead of Windows Server Update Services (WSUS) checkbox. options to enable

  5. Make sure Windows Updates Service is set to Manual or Automatic to apply this fix. Our default images are set to disabled, and the issue continued until that seemingly obvious change was made.

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