On several Visual Studio version, when you try to publish using FTP, you get this error:
… The components for communicating with FTP servers are not installed.

In case of Visual Studio 2013 and 2015, follow these steps to avoid this error:
– Install the latest Visual Studio update
– Remove Xamarin (from Control Panel)
– Remove Visual C++ Redistributable (x86) (from Control Panel)
– Install Visual C++ Redistributable (x86)
– – for Visual Studio 2013: https://www.microsoft.com/en-us/download/details.aspx?id=40784
– – for Visual Studio 2015: https://www.microsoft.com/en-us/download/details.aspx?id=48145
– Reboot (you have to do, otherways it does not work).

After these steps, it will work again.