category link not working for a specific slug, works for others

Permalinks are cached in wp_options and every time you update them in the code, you should flush them.

Visiting wp-admin/options-permalink.php does the trick. Optionally you can try to resave that page, despite the resave is not needed, but is worth nothing.

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