Remember the good ol days when installing .Net Framework Features on Windows Server 2008 R2 just required ticking off a checkbox when adding features? I miss those days.
Server 2012 has made the process a bit more…elaborate, so to speak. The 3.5 Framework Features are no part of what is called Features on Demand, you can read more about it here. When you use Server Manager and select the Framework 3.5, you’ll now see this dialog with some extra options below, which if you are anything like me, will ignore completely and just click Next Next Next:
After you click next, you will be greeted with this message:
Restart the wizard, but this time around click on that link to “Specify an alternate source path”:
Now, you MUST insert the DVD of Server 2012 or mount an ISO and point to the following path (assuming your Windows Server 2012 mounted media is in D:)
The install will now finish successfully. If you point to the sourcessxs directory via a UNC path, it will fail (at least it failed on me).