I got a FTP error 530: maximum number of clients from your host are already connected!
My FTP program displays 'error 530: maximum number of clients from your host are already connected'. I also get an error '425 Unable to build data connection'.
Try to reduce the number of open FTP sessions (if your FTP program lets you configure the maximum number of simultaneous connections, set it to 3). It could also be that you have uncontrollable FTP sessions running, then try to restart your FTP client program or if possible restart your computer to reset the process table.