Plesk

Changing the Locale Code

The code of the default American English locale is en-US (en_US in
some files). You need to change it to that indicating your language and
country according to ISO standards. To find the required locale code,
see the Appendix. Locale Codes section.

Changing the Locale Code in File Names

Change the locale code in names of the following directories, and the
names of all files contained within:

On Linux:

On Windows:

You also need to change the locale code in the following entries found
in the /usr/local/psa/admin/plib/locales/en-US/messages_en-US.php
file (on Linux) or the
%plesk_dir%adminpliblocalesen-USmessages_en-US.php (on Windows):

@include('devmessages_en-US.php');
@include('common_messages_en-US.php');
@include('common_cli_messages_en-US.php');
@include('conhelp_en-US.php');