‘morning all
I’d found many people with this problem, but no resolutions that worked for me.
Mine is now sorted and this may be the problem for others.
Assuming that you can ftp to your server using either a ftp client or command line ftp. Then check in a browser whether you can connect to ftp://ftp.<your domain>. If after entering the logon details it fails, either with a vague error (IE5) or “425 – Can’t open data connection” then although port 21 is open on your server for client connections, it is probably blocked by the firewall when accessed via a browser.
Once this is opened, by you or your hosting company, all might be well.
I think – might be wrong – that if WordPress gets an error when attempting to ftp, there may be only a limited range of expectations, ie wrong user/password, “FTP hostname is required” with the assumption that failure that is not the former must be the latter.
This may lead to the confusion I and others have had, where clearly the host name is correct but WordPress says it’s wrong, leading us to miss the obvious. ie WordPress is operating through a browser connection.
Hope it helps – it did me ??
cheers
Rod