WordPress 3.0 introduced wp_favicon_request() to avoid the performance hit that comes from serving a full 404 page on every favicon request. While that function works as intended, it doesn’t offer enough flexibility.

As of WordPress 5.4, theme and pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the WordPress.org Plugin Directory https://wordpress.org/plugins/ or can be cost-based plugin from a third-party authors can manage favicon requests much more flexibly, with the following logic:

• If there is a Site Icon set in CustomizerCustomizer Tool built into WordPress core that hooks into most modern themes. You can use it to preview and modify many of your site’s appearance settings., redirect /favicon.ico requests to that icon.
• Otherwise, use the WordPress logo as a default icon.
• If a physical /favicon.ico file exists, do nothing and let the server handle the request.

This logic will only work if WordPress is installed in the root directory.

With these changes, /favicon.ico handling is now more consistent with /robots.txt requests.

New functions & hooksHooks In WordPress theme and development, hooks are functions that can be applied to an action or a Filter in WordPress. Actions are functions performed when a certain event occurs in WordPress. Filters allow you to modify certain functions. Arguments used to hook both filters and actions look the same.

WordPress 5.4 introduces a bunch of new functions and hooks for favicon handling:

• is_favicon() conditional tagtag A directory in Subversion. WordPress uses tags to store a single snapshot of a version (3.6, 3.6.1, etc.), the common convention of tags in version control systems. (Not to be confused with post tags.) to complement is_robots().
• do_favicon action to complement do_robots and use it in template loader. This hook will be fired when the template loader determines a favicon request.
• do_favicon() function, hooked to the above action by default, to complement do_robots().
• do_faviconico action to complement do_robotstxt, for plugins and themes to override the default behavior. This hook will be fired when displaying the favicon file.

With the above logic, do_favicon redirects to the Site Icon if it exists, or to WordPress logo as a default icon, using the following code:

function do_favicon() {
    /**
     * Fires when serving the favicon.ico file.
     *
     * @since 5.4.0
     */
    do_action( 'do_faviconico' );

    wp_redirect( get_site_icon_url( 32, admin_url( 'images/w-logo-blue.png' ) ) );
    exit;
}

Themes and plugins developers can use do_faviconico action to override the default behavior.

Deprecations

• wp_favicon_request() is now deprecated in favor of do_favicon().

For reference, see the related ticketticket Created for both bug reports and feature development on the bug tracker. on WordPress CoreCore Core is the set of software required to run WordPress. The Core Development Team builds WordPress. TracTrac An open source project by Edgewall Software that serves as a bug tracker and project management tool for WordPress.: #47398

#5-4, #dev-notes, #favicon