Craft 3 / Commerce 2 + Multisite & COMMERCE_PAYMENT_CURRENCY I've just done a Craft 2 > Craft 3 upgrade, and it previously used different locales to change the default currency, depending on the locale.

In Craft 2, I would set COMMERCE_PAYMENT_CURRENCY in my index.php file (https://docs.craftcms.com/commerce/v2/payment-currencies.html#switching-currencies) so that it would set the currency for that specific site.

But in Commerce 2 this doesn't seem to be working at all.

My current setup is:

/web 
   index.php
   /europe
      index.php


And in the /europe/index.php I've got:

&lt;?php
/**
 * Craft web bootstrap file
 */

// Set path constants
define('CRAFT_BASE_PATH', dirname(__DIR__, 2));
define('CRAFT_VENDOR_PATH', CRAFT_BASE_PATH.'/vendor');

define('CRAFT_SITE', 'en_eur');

define('COMMERCE_PAYMENT_CURRENCY', 'EUR');

// Load Composer's autoloader
require_once CRAFT_VENDOR_PATH.'/autoload.php';

// Load dotenv?
if (class_exists('Dotenv\Dotenv') &amp;&amp; file_exists(CRAFT_BASE_PATH.'/.env')) {
    Dotenv\Dotenv::create(CRAFT_BASE_PATH)-&gt;load();
}

// Load and run Craft
define('CRAFT_ENVIRONMENT', getenv('ENVIRONMENT') ?: 'production');
$app = require CRAFT_VENDOR_PATH.'/craftcms/cms/bootstrap/web.php';
$app-&gt;run();



I know this  file is being picked up when I go to http://website.local/europe, because if I delete the contents, or change the CRAFT_SITE it reacts correctly.

Just not working for Commerce 2.
It seems the const COMMERCE_PAYMENT_CURRENCY isn't checked and set inside Commerce 2 (It was in Commerce 1)

So I created a PR for this issue:

https://github.com/craftcms/commerce/pull/999