Latex error ”Unable to read environment locale:exit now”

Emacs 25.3 with YateX outputs the error saying "Unable to read environment locale:exit now".
The following has fixed the problem:
'M-X setenv' and change 'LANG' into 'en_US.UTF-8', where "M-X" means pushing "Esc" key and "x" key.
Refer: LuaTeX error: "Unable to read environment locale:exit now." - TeX - LaTeX Stack Exchange

「Unable to read environment locale:exit now」というエラーをEmacs with YaTeXが出力したので，'M-X setenv' をして，'LANG'を'en_US.UTF-8'に変更したら治った．ここで"M-X"は"Esc"キーと"x"キーの押下げ．