.NET Framework 3.5 Features fails to install

I just blogged about a gotcha in the Azure Pack install when configuring Site Roles and realized that the post was very narrow so wanted to post one a bit more general.

Have you tried to install .NET Framework 3.5 on Server 2012 and you get the error  “Installation of one or more roles, role services, or features failed”

This is because .NET 3.5 is not available after you install Server 2012.  In order to install .NET 3.5 Features you must have either a network share with the Side by Side (SXS) folder or the installation media.

To successfully install .NET 3.5, go through the normal process of adding the feature, when you get to the “Confirm installation selections” screen click the “Specify an alternate source path” link.

When you do so you will get the following window which states what I said. “Source files for .NET Framework 3.5 Features are not installed as part of the typical installation.

Enter in your source path (mine was my install media) and click OK. The install will now complete successfully.