You cannot build the project when you use an XOML-based activity in Visual Studio 2013 RC

Symptoms

Consider the following scenario:

You have Microsoft Visual Studio 2013 Release Candidate (RC) installed on your computer.
You have an older version of Visual Studio, such as Microsoft Visual Studio 2012, installed on the same computer.
You uninstall the older version of Visual Studio.
You create a Microsoft .NET Framework 3.5-based project that is created from a workflow project template in Visual Studio 2013 RC.
You add an XOML-based activity to the project.

In this scenario, you may be unable to build the project, and the activity cannot automatically generate the event handler code.

This issue occurs because the build action of the XOML-based activity is set to "None" instead of to "Content."

To work around this issue, run the Visual Studio 2013 RC repair program. To do this, follow these steps:

Click Start, click Control Panel, click Programs, and then click Programs and Features.
Right-click the version of Visual Studio 2013 RC that you have installed, and then click Change.
hen the Visual Studio 2013 RC Setup wizard opens, click Repair.