[Toxin]

Thanks to the French Fedora web site I've found the error,
"action" was missing in the jail.conf

[pure-ftpd]

enabled = true
port = ftp,ftp-data,ftps,ftps-data
filter = pure-ftpd
action   = iptables[name=PUREFTP, port=ftp, protocol=tcp]
           sendmail-whois[name=PUREFTP, dest=you@mail.com]
logpath = /var/log/messages
maxretry = 6

Now it works perfect, no more errors on start of Fail2ban