FTP site cannot be started

You can use the netstat -anbcommand to see which process is listening on port 21.

Be sure to run that from an elevated command-line.

Edit: For clarification, here is what the -anb option does:

• a Displays listening ports as well as open connections
• n Doesn't attempt to resolve host names and port numbers (makes it much faster)
• b Tries to display the process associated with each specific socket.

Restarting the windows service "Microsoft FTP Service" does the trick for me on Windows 10.

Original Source:

http://clintboessen.blogspot.com/2013/03/the-ftp-site-cannot-be-started-another.html?_sm_au_=iVV766VqSV6HNtVN