That's expected. You get that when you connect to a server for the first time.
See Verifying the Host Key.
Typically, one just clicks Yes.

I can connect to my host Netfirms.com with standard FTP. I no longer have FileZilla but
I tried the suggested change to the setup and got this message (which I don't understand).

If FileZilla can connect, then WinSCP should be able too.
More likely is that the instructions are incorrect or the server is broken.

Note that the text instructions (contrary to the screencast) say the hostname to use is ftp.PrimaryDomain, not sftp.PrimaryDomain.
https://www.netfirms.com/help/article/ftp-how-to-connect-using-an-ftp-client
Try that.

Can you actually connect with FileZilla or any other client? If you can connect, please post logs both from FileZilla and WinSCP.

I can connect just fine using WinSCP to my host netfirms.com with standard FTP but when I attempt SFTP it's not connecting. I used the recommended settings netfirms.com shows (for FileZilla.) They don't list WinSCP but they do list other clients like (CuteFTP). Is it possible netfirms.com technology doesn't support WinSCP? See attachments please. Thanks for any help.

Panonut