Fce setLocale() does not work properly on the server

I use the setLocale () function to set the language of the error messages.

it works well on localhost (win, xampp), but not on server (unix).

in app.php is set:

PHP Code:

public $defaultLocale = 'en';
public $supportedLocales = ['en', 'cs']; 


in controler is set:

PHP Code:

$this->request->setLocale('cs'); 


On localhost is error messages in 'cs', but on server only in 'en'.

I listed the request

PHP Code:

var_dump($this->request); 


after the setLocale() and the localhost is

Code:

["locale":protected]=> string(2) "cs"

on the server is

Code:

["locale":protected]=> string(2) "en"

please, give me an advice