FYI
When updating a URL, the Webmaster/mistress must delete the old files on the Remote side (server side) of the FTP, then replace them with the updated files from the Local side (their system). While this transition is taking place, the URL is unavailable.
Or, it may be that the FSM, or some Downstream Server, is experiencing trouble, in which case, alternate paths will eventually correct the problem on its own..... just chill a little while and try again later.
Frank