Error installing .NET Framework 3.5 on Windows 2012 (R2)

I frequently get questions from people about problems with installing .NET 3.5 features on Windows Server 2012 and 2012R2.
Most problems are solved when adding the sources directory from the Windows installation media (so mount the ISO) during the GUI installation.

feature installation

alternate source

Another way to do it, is by using the following command:
Dism /online /enable-feature /featurename:NetFx3 /All /Source:d:\sources\sxs /LimitAccess

This all works fine, but sometimes the .NET framework installation still fails. you keep getting the following error: 0x800f081f. The source files could not be found. Install Error!

command line installation

The cause for this error can be that you can’t install .NET Framework 3.5 if you have additional Language Packs installed

The only way to solve this is to remove the additional Language Packs (in my case Dutch) via lpksetup and then installing .NET Framework.

lpksetup2

uninstall2

MUI interface2

 

Dont forget to install the Language Packs again afterwards!
If this doesn’t work there are two other options to try:

  • It seems that Windows Security Update: KB2966827 could one of the causes, that .Net Framework can’t install. Remove this update and then try installation again.
  • As a long shot you can try installing the core version of .NET 3.5 with this command line
    Install-WindowsFeature –name NET-Framework-Core –source <drive>:\sources\sxs
    this also seems to do the trick sometimes with Windows Server 2012 R2.

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