Custom taxonomy returns 404

You cannot have a rewrite slug of "https://wordpress.stackexchange.com/". Note that using a slug of '', which you will find floating around, will not work for the latest WordPress versions either. If you want a url like http://domain.com/custom-post, there are no bullet-proof solutions, but the answer to this question will give you some leads: Remove slug from custom post type post URLs

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)