Homepage with www. status code 404

Hi all and thanks for taking the time to read my post.

My homepage http://enviedelecture.fr/ is working fine (status code 200 in https://httpstatus.io/) but “http://www.enviedelecture.fr/” cannot be found (status code 404 in https://httpstatus.io/).

When trying to add “http://www.enviedelecture.fr/” to Google Search Console, I also get the error message: “Your site’s home page returns a status of 404 (Not found) instead of 200 (OK).”

The domain is 1year+ old.

How can I solve this problem? What could be causing the error?

Thanks a lot for your help!