ASP.NET 4.5 has not been registered on the Web server

Maybe you have to execute the following in the Visual Studio Tools command prompt:

aspnet_regiis -i

You can read more about the ASP.NET IIS Registration Tool (Aspnet_regiis.exe) here.

On Windows 8.1, since .NET 4.5 is built-in, the fix is to run this from an administrative command-prompt:

dism.exe /Online /Enable-Feature /all /FeatureName:IIS-ASPNET45

If you've installed .NET framework 4.6, you may see this error due to a VS bug. Workarounds and resolutions here:

http://blogs.msdn.com/b/webdev/archive/2014/11/11/dialog-box-may-be-displayed-to-users-when-opening-projects-in-microsoft-visual-studio-after-installation-of-microsoft-net-framework-4-6.aspx

EDIT:

As noted in some of the comments, this can happen behind the scenes after upgrading to Windows 10 or Visual Studio 2015.