Hello, I have the same problem. I temporaly solved by change the system language from fr_FR.UTF-8 to en_US.UTF-8 by the command dpkg-reconfigure locales. You can also fix juste for one with this syntax : LANG=C /usr/lib/nagios/plugins/check_ntp_time -H ntp.ovh.net -w 1 -c 2 Regards, Nico.