Display the current post author and his url in the post header

You are probably calling it too early and the context for the current post is not filled yet. get_author_posts_url() accepts author’s ID as first argument, You probably need to retrieve and pass that to it, similar to how you retrieve the info for following call.

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