How to link avatar and nickname to profile

This a short compilation of the multiple comments above, so that future visitors don’t have to read each and every one of them.

First of all, the_author_posts_link() is a deprecated function since version 2.1, so get_author_posts_url() or the_author_posts_url() should be used instead http://codex.wordpress.org/Function_Reference/get_author_posts_url

The the/get_author_posts_url() takes an argument that requires “ID of the author whose URL should be retrieved.”, so the_author_posts_url( get_the_author_meta( 'ID' ) ) will work, and if you decide to use the get_author_post_url() instead of the_author_posts_url() don’t forget to echo it out.