I solved the problem. Please follow below.
The locale default settings on the ubuntu server must also include /var/www/stalker_portal/server/config.ini
My ubuntu server settings
locale -a
en_US.utf8
Stalker_portal content in the initial setup
default_locale = ru_RU.utf8
allowed_locales = ru_RU.utf8
allowed_locales = en_GB.utf8
allowed_locales = uk_UA.utf8
allowed_locales = pl_PL.utf8
allowed_locales = el_GR.utf8
allowed_locales = nl_NL.utf8
allowed_locales = it_IT.utf8
allowed_locales = de_DE.utf8
allowed_locales = sk_SK.utf8
allowed_locales = es_ES.utf8
I changed line "allowed_locales = en_GB.utf8" to my ubuntu locale settings as "allowed_locales = en_US.utf8" in the /var/www/stalker_portal/server/config.ini