I just got a new computer and installed FileZilla on it. When I tried to update my website, there was a scary message about a potential security breach and I didn't know what to do.
The server wants to identify your computer before it allows you on the server. This message will appear each time you configure your uploads on a different computer. If you do not tell the server to accept uploads from your computer every time, you will see the message again. Tell the server to accept your information from this specific computer every time you try to log in.