If you’re getting the following error:
The version of the .NET Framework launch condition ‘.NET Framework 4’ does not match the selected .NET Framework bootstrapper package.
..chances are your .NET Framework prerequisite under the setup project doesn’t match one or more of the projects added to the setup project.
Check which .NET Framework you have selected as a prerequisite and if it matches all projects added to the setup package. If that still doesn’t remove the warning, select the setup project, click on the “Launch Conditions Editor” button on the Solution Explorer toolbar, select the “.NET Framework” (probably underlined with a red squiggly line) and check the Properties window to see if the Framework selection in the dropdown also matches all projects.
See this blog post for more information on the Conditions Editor.