After installing WordPress version 4.6.1 and WooCommerce version 2.6.6, both with the default enabled language, English (United States), I followed the steps below and had the translation successfully installed and working:
Set a language for your WordPress installation
- Click on the General sub-menu item under Settings from the Dashboard of your WordPress installation, and scroll down to the last edit option available: Site Language;
- there, select your desired language, here: Slovenščina, then, click on the "Save Changes" button in order to effect your modification.
At this stage, though the language base of your WordPress installation has been updated, you will realise that your WooCommerce pages will still be displayed in it's default initial installation language: English (United States).
Now, hover on your Dashboard menu item and click on the Update Core (both now displayed in your newly defined WordPress installation language).
You should already see there a notification about a number of updates available; our focus here is on the available translation updates.
- Scroll down the page and click on the "Update Translations" button under the Translations section (all still in your newly defined WordPress installation language) in order to update the language definition for readily modifiable WordPress packages, which includes WooCommerce.
After a successful update, you may now click on the WooCommerce menu; everything should be automatically available in your newly defined WordPress installation language (except untranslated strings).
Should you chose to update your WooCommerce language over FTP, do make sure you upload your
.po files to the
plugins directory under
wp-content/languages so as to make them readily accessible for use; NOT immediately under the
wp-content/languages as shown on your attached screenshot: that accounts for the wrong listing of
woocommerce-sl_SI as an installed Core WordPress translations (refer to your first screenshot above; Site Language dropdown list).
.po files to your
wp-content/plugins/woocommerce/i18n/languages instead of the later directory as specified above will equally work.
Please note: the default installation language will be used for your WooCommerce installation instance should there be no corresponding language set
.po files matching your WordPress installation language; either: WordPress is
sl_SI, WooCommerce should equally be