While creating one of many Lync scenario labs, I chose to install SQL Server 2012 instead of my usual install of SQL 2008 on Windows Server 2012. Going about my happy routine after clicking install, I expected install to complete when I returned a few hours later. Murphy never fails though. And here I am looking at install error instead!
The error read:
TITLE: Microsoft SQL Server 2012 Setup
——————————The following error has occurred:
Error while enabling Windows feature : NetFx3, Error Code : -2146498298 , Please try enabling Windows feature : NetFx3 from Windows management tools and then run setup again. For more information on how to enable Windows features , see http://go.microsoft.com/fwlink/?linkid=227143
So it wants me to install NetFx3. Should be easy. The requirement basically meant it needed .Net Framework 3.5. All I have to do is run the following from PowerShell:
Add-WindowsFeature NET-Framework-Core
Well, what do I know? It gave me an error too!
Add-WindowsFeature : The request to add or remove features on the specified server failed.
Installation of one or more roles, role services, or features failed.
The source files could not be downloaded.
Having seen this error, I knew what I had to do but let me illustrate. When you run the following at PowerShell prompt, you will notice that not only the “Installed” state is set to “False” indicating it’s not installed but “InstallState” states “Removed”:
Get-WindowsFeature Net-Framework-Core | FT name,install*
Name Installed InstallState
—- ——— ————
NET-Framework-Core False Removed
All it means is that the standard install of Windows Server 2012 does not even install binaries required to enable feature. If you want to install this feature, you will need side-by-side assembly source, usually the installation media. If you are curious about what side-by-side means, check out wiki article here.
The solution here sounds simple. Just run:
Add-WindowsFeature NET-Framework-Core -Source D:\sources\sxs
This assumes D is your CD drive which has Windows Server 2012 installation media. Now I should warn you, this won’t work if you have run Windows Update and applied patches after installing Windows Server 2012 and before trying to install SQL Server 2012! If you want answer to obvious “why?”, you should read my previous post explaining how to resolve Error: 0x800f0906 adding Windows features.
Don’t you love rabbit holes we deal with in IT? 
SQL Server 2012 will run some tests, in my case it showed a warning on the FIREWALL, because it was enabled. The warning was for “not forgetting” to open the specific ports for the communication.