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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?


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.

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If you want to download and install it, you must write: dism.exe /online /enable-feature /featurename:NetFX3 /all (without specifying the /Source) –  SEARAS Feb 1 '14 at 12:20
@SEARAS did not work –  Micky Duncan Sep 18 '14 at 2:38
If you, like me, have tried all of these and still nothing, try disabling UAC. I had to end up mounting an ISO and providing alternate source, and disabling UAC to get it to install properly –  Cougar9000 Oct 9 '14 at 19:33

6 Answers 6

Step 1: Uninstall any of these updates in: Control Panel -> Uninstall a Program -> View Installed Updates.

  • KB2966826
  • KB2966827
  • KB2966828

Step 2: Then, retry installing the feature using the GUI (Server Manager), command line (dism), or PowerShell (Install-WindowsFeature)

Additional information on enabling features

Method 1: Using GUI - Server Manager

Server Manager -> Add Roles and Features -> Role-based or feature-based installation -> Select Server -> Features -> .NET Framework 3.5 Features

Method 2: Using Command Line - dism

dism : Using local installation media/Windows update/WSUS

dism /online /enable-feature /featurename:NetFx3 /all

DISM: With a local 'Alternate Source'

dism /online /enable-feature /featureName:NetFx3 /all /limitAccess /source:drive_letter:\sources\sxs

Please replace drive_letter with the drive letter of your local drive where the installation files reside

DISM: With a remote 'Alternate Source'

dism /online /enable-feature /featurename:netfx3 /all /LimitAccess /source:\\share_name\sources\sxs

Please replace share_name with the the UNC of the shared location where the installation files reside

Method 3: Using PowerShell

PowerShell: Using local installation media/Windows update/WSUS

Install-WindowsFeature –name NET-Framework-Core

PowerShell: With a local 'Alternate Source'

Install-WindowsFeature –name NET-Framework-Core –source x:\sources\sxs /source:drive_letter:\sources\sxs

Please replace drive_letter with the drive letter of your local drive where the installation files reside

PowerShell: With a remote 'Alternate Source'

Install-WindowsFeature –name NET-Framework-Core –source \\share_name\sources\sxs

Please replace share_name with the the UNC of the shared location where the installation files reside

Helpful Resources:



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This would be a much better answer if it had a real explanation. Simply linking to an external site is not really useful. –  Michael Hampton Oct 2 '14 at 21:49
Answer has now been updated with additional information. I faced this issue and just resolved it. Hope it helps someone else too –  slayernoah Oct 3 '14 at 20:34

After trying to install .net 3.5 on Windows Server 2012 for 3 days, I have finally managed to do it.

The key for me was to check the installed windows updates for KB2966826, KB2966827 and KB2966828. I had KB2966827 installed and after removing it, I could install 3.5 via Server Manager.

See this article http://www.askvg.com/fix-0x800f0906-and-0x800f081f-error-messages-while-installing-net-framework-3-5-in-windows-8/

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That worked for me, for some reason Windows install this update even if you haven't installed .net 3.5 on your system, making it impossible to install. More info: support.microsoft.com/kb/3002547 –  ojovirtual Sep 24 '14 at 8:56

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.


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.
  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) check box.
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Based on the OP's comment, this appears to have been the correct answer. –  Michael Hampton Apr 5 '14 at 4:32
Did not work for me, it was already on this setting –  Micky Duncan Sep 18 '14 at 2:40

Give this command on your Comman Prompt and modify the source path section in the command to point to your windows instalation, Source, Sxs folder.

dism.exe /online /enable-feature /featurename:NetFX3 /Source:D:\sources\sxs

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The OP said in his question that he already tried that and it didn't work because he doesn't have an install disk. He has also already posted an answer detailing what did work. –  Ladadadada Sep 18 '13 at 11:17

I have tried everything suggested all over net - but nothing worked since I didn't have source disc. Luckily, I eventually remembered Web Platform Installer - download it, find .NET Framework 3 - install:


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I haven't tried installing .NET 3.5 on Windows 2012 myself, but the following link describes how to do it. Maybe you'll get some hints there:


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Thanks but this requires installation disk. I want to do it by downloading requisites from internet. –  Tim Tom Jan 7 '13 at 8:01
I believe you can just download the files from the Internet, and then extract the ones you need to a directory. Another way of installing .NET 3.X is to mount the installation media and run the following command: Dism /online /enable-feature /featurename:NetFx3 /All /Source:x:\sources\sxs /LimitAccess –  Nils Magne Lunde Jan 7 '13 at 8:32
Do you mean download full Windows Server 2012? just to install .Net 3.5? I already download offliner installer of .Net 3.5 and it's an exe and when I run it, it throws error as shown on my question: serverfault.com/questions/463616/… –  Tim Tom Jan 7 '13 at 8:42
Thanks for your help. The actual answer is: stackoverflow.com/questions/14192244/… –  Tim Tom Jan 7 '13 at 9:54
@TimTom Would you kindly post that as an answer and mark it accepted when you are able. –  jscott Aug 3 '13 at 2:48

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