I’ve encountered this situation before with Server 2008 R2 and it has been a pretty popular article. I’m trying to install SQL Server 2008 R2 and it gives me a message about .NET Framework 3.5 needing to be installed as a prerequisite. However, the framework can’t just be downloaded and installed. You have to use the Server Manager. Here are some updated instructions to install .NET Framework 3.5 on Server 2012.
The error I was receive reads:
The following feature couldn’t be installed:
.NET Framework 3.5 (includes .NET 2.0 and 3.0)
Windows Server roles and features cannot be automatically installed or uninstalled via the Windows Features Control Panel.
To install Windows Server roles and features, start Server Manager, or use the Server Manager cmdlets for Windows PowerShell. For more information, see: Server Manager Help.
Opening Server Manager as instructed (by default, it has an icon pinned to the Taskbar), I clicked on Number 2 “Add roles and Features” from the Server Manager Dashboard.
After clicking on this link, the Add Roles and Features Wizard pops up. I choose Role-based or feature-based installation and click ‘Next’.
I want to install it on the local server I was remoted into, so I chose it from the list and clicked ‘Next’.
At this point, I didn’t need to any roles, so I just clicked ‘Next’ to get to choosing Features to install.
Finally making it to ‘Features’, I expanded the .NET Framework 3.5 Features and checked the top level and the .NET Framework 3.5 (includes .NET 2.0 and 3.0). Then I clicked ‘Next’.
The following screen provides a confirmation of what you selected in the previous screens. As you can see from the screen below, I only have .NET 3.5 selected. From this screen you can also specify an alternate source path to point to either the Server 2012 setup files or the Feature you are installing files. I left everything as default and hit the ‘Install’ button.
The above steps worked correctly for me to get .NET Framework 3.5 installed. The first time, however, I ran into a little hold-up. If you don’t have the source files locally, the installer will attempt to download the source files from Windows Updates servers. This would work fine but my Group Policy for the server was redirecting the computer to use a WSUS server on the LAN. Since the WSUS didn’t have the needed source file, it gave an error and ended the install unsuccessfully.
I found an article from Microsoft’s MSDN library and it gave a few options to solve the problem. I chose the straight-forward solution listed for Enterprises. I created a Registry key and value as directed.
This tells the Features Installer to bypass the WSUS and go to Windows Updates. While it consumes bandwidth to the web and can take some time to download the sources, it works. I set this registry key and reran the Installer and received the feature has been successfully installed message.
You can also configure this setting in Group Policy. Under Computer Configuration -> Administrative Templates -> System, you will find the setting “Specify settings for optional component installation and component repair” which you can select to bypass WSUS and go straight to Windows Updates for repair sources.
After completing the install through the Role Management Tool, I was able to successfully install SQL Server 2008 R2 without it complaining about the prerequisite .NET Framework 3.5 not being installed any more.