Проблема:

perl: warning: Please check that your locale settings:
LANGUAGE = (unset),
LC_ALL = (unset),
LC_CTYPE = "UTF-8",
LANG = "en_US.UTF-8"
are supported and installed on your system.
perl: warning: Falling back to a fallback locale ("en_US.UTF-8").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory

Решение «на лету» с консоли (временное до перезагрузки):

root@srv:~# export LANGUAGE=en_US.UTF-8
root@srv:~# export LC_ALL=en_US.UTF-8

Решение постоянное:

root@srv:~# nano /etc/default/locale

LANGUAGE=en_US.UTF-8
LC_ALL=en_US.UTF-8

На случай, если dpkg-reconfigure locales, locale-gen не принесли ожидаемого результата.