Setup proper 301 redirect for deleted tags

Question

I recently deleted a large number of tags (~20k-25k) from one of the categories that publishes news items. These tags were contributed by our authors and added no value to the site. As a result, Google's bot is now noticing a LARGE number of 404 errors (~90k) on our site and as a results has pushed our rankings down. Though Google says that 404 errors don't affect, our observation is bit different.

After experiencing the downwards traffic for over a month now, I've decided to redirect all the 404 pages originating from the deleted tags to home-page permanently. I'm not sure whether this is a right step; but that seems to be the only option that I have.

My requirements:

For every 404 resulted on domain.com/tag/ , I want to setup 301 redirect to home page.

I'm a complete noob when it comes to redirects and can't take chances on messing up with these.

Answer 1

Sounds like an easy task to do. I think hooking into 'template_redirect' and conditionally triggering redirect is the way to go.

EDIT: Seems is_tag() isn't reliable once 404 is triggered. That's why we need to look into the query vars to figure out if it's really a tag query or not.

function redirect_404_tags_wpse67077() {
    global $wp;
    if ( ! empty( $wp->query_vars['tag'] ) && is_404() ) {
        wp_safe_redirect( home_url('/'), 301 );
        exit;
    }
}

add_action( 'template_redirect', 'redirect_404_tags_wpse67077', 1 );