How to base64 encode/decode accents characters

I am trying to base64 encode a string which contains accent characters. echo FILE_DATE.Ç | iconv -t utf-8 | base64 But it is giving error iconv: (stdin):1:10: cannot convert locale outputs:

LANG=
LC_CTYPE="C.UTF-8"
LC_NUMERIC="C.UTF-8"
LC_TIME="C.UTF-8"
LC_COLLATE="C.UTF-8"
LC_MONETARY="C.UTF-8"
LC_MESSAGES="C.UTF-8"
LC_ALL=