Linux : setlocale: LC_CTYPE: cannot change locale (UTF-8) after Debian 12 to 13 upgrade

By | August 2, 2026

After a successful upgrade from Debian 12 (Bookworm) to 13 (Trixie), you may notice the following output error when logging into a shell session :

warning: setlocale: LC_CTYPE: cannot change locale (UTF-8): No such file or directory

Here is who you can quickly resolve this issue with the following commands (as root or using sudo) :

locale-gen en_US.UTF-8
update-locale LANG=en_US.UTF-8

Alternatively, you may also attempt to append the following manually to “~/.bash_profile” :

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8