This warning or error is part of the OpenSSH server and macOS or OS X ssh terminal client issues. It can be fixed using various methods.
Understanding LC_* environment variables
Type the following command on the remote server to display all locales supported by Glibc:
$ locale -a
Next, type the following command to display settings on your local system (OSX/Unix/Linux based desktop):
The above commands display the country and language names, the character encoding used by the locale.
How to fix "setlocale: LC_CTYPE: cannot change locale (UTF-8)"?
Solution #1: using the Terminal app on OS X
Open your MacOS Terminal app then click on
Terminal > Preferences > Select Terminal type such as Basic (default) > Advanced tab
Make sure that the ‘Set locale environment variables on startup’ is unchecked.
You must close all ssh sessions and relaunch the Terminal app.
Solution #2: Via OpenSSH
Here, we will prevent OpenSSH Client from sending the LC_* variables on OS X / Linux / Unix desktop
Edit /etc/ssh/ssh_config or /etc/ssh_config file, enter:
$ sudo vi ~/.ssh/config
Remove or comment out as follows:
#SendEnv LANG LC_*
Save and close the file.
Solution #3: Installing localedef command
Finally, you can fix this problem by either installing the desired locale using the localedef command or consider choosing a different locale in locale/remote system:
# localedef -i en_US -f UTF-8 en_US.UTF-8