Installing NetFx3 on Windows Server 2012

Okay… I am installing SQL Server 2012 on a Windows Server 2012 box, there shouldn’t be any problems.  Everything is proceeding normally until I get this message:

Error while enabling Windows feature : NetFx3, Error Code : –2146498298 , Please try enabling Windows Feature : NetFx3 from Windows management tools and then run setup again.

No problem… I know how to install Windows Features; I start the Add roles and Features Wizard and go looking for NetFx3… it’s not there.

Problem.

It turns out that Windows Server 2012 does not include NetFx3 when it is installing.  It doesn’t mean that it is gone, but it does have to be installed separately.  Here’s what you do:

1) Insert your Windows Server 2012 media.  As I was installing SQL Server in a Hyper-V VM I ejected the SQL media and attached my Windows Server 2012 ISO.  I then checked to see what drive letter it was (D:).

2) I opened a Command Prompt with administrative credentials.  From the Start Screen I typed CMD but instead of clicking on it or pressing ENTER I right-clicked, and at the bottom clicked on Run As Administrator.

3) From the Command Prompt I typed the following command:

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

The Deployment Image Servicing and Management tool is one of the easiest ways to install features in Windows when the GUI fails you. 

Note: Unfortunately, if you encounter this error you will have to restart your installation of SQL Server.  That doesn’t mean you should cancel it out at this point… what I did was I left the error message on the screen while I resolved the NetFx3 issue, and then let it resume.  The SQL Server installation succeeded, with several failures.  I then went back and re-installed SQL on top of the old, with the features that I needed.  It worked just fine for me, and it should for you.