Warning is shown on remote system when user is connected using SSH (user host locale are forwarded to remote machine which doesn't support it)
perl: warning: Setting locale failed. perl: warning: Please check that your locale settings: LANGUAGE = (unset), LC_ALL = (unset), LC_TIME = "pl_PL.UTF-8", LC_MONETARY = "pl_PL.UTF-8", LC_CTYPE = "pl_PL.UTF-8", LC_COLLATE = "pl_PL.UTF-8", LC_MEASUREMENT = "pl_PL.UTF-8", LC_NUMERIC = "pl_PL.UTF-8", LC_PAPER = ""pl_PL"", LANG = "C" are supported and installed on your system. perl: warning: Falling back to the standard locale ("C").
On remote machine type:
locale-gen pl_PL.ISO-8859-2 locale-gen pl_PL.UTF-8 dpkg-reconfigure locales