You may get this message when connecting to a server for following reasons:
ftp://ftp.example.com) as hostname on Login dialog instead of actual hostname (e.g.
open site_namesyntax in an environment, where stored site
site_namedoes not exist. The
site_namewill then be used as a hostname instead. See Why does WinSCP not work in a new environment (operating system, machine, user account, network), when it works for me in a different environment already?
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