How to have multilingual custom 404? I have a multilingual Drupal 7 site for which I have set up a translated 404-page accessed at mydomain.com/404 and mydomain.com/en/404. In the Drupal settings for 404-page I enter just the path 404.

However, when visiting a non existant URL on the English version, the default language is still being used.

What did I miss?
With i18n module pack, there is a module for translating settings, like front page and 404 pages. This means you can setup your 404 page per language, fx node/1 for en and node/2 for fr etc.