invalid characters in password error

When I enter in a password that has a "@" in it in the SSH server backup destination section of Webmin -> Backup Configuration Files -> Backup Now, I get the following error:

Error
Backup failed : Invalid characters in FTP server password
Status: 
Closed (works as designed)

Comments

That is expected - an FTP backup URL is formatted like :

ftp://username:password@host/file

So if the password contains an @, it will break this formatting. You need to switch to a password without an @ (or colon) in it.