Miscellaneous developer changes in WordPress 6.6

Table of contents


Allowed disabling autosave support for individual post types

[58201] added a way to allow disabling autosave support for individual post types. Not all post types support autosaving. By making autosave a post type feature, support can be more granularly handled without any workarounds or hardcoded allowlists. For backward compatibility reasons, adding editor support implies autosave support, so one would need to explicitly use remove_post_type_support() to remove it.

See #41172 for more details.

Bundled Theme

Twenty Sixteen: Fixed mismatch of visual and DOM order of elements

Starting in Twenty Sixteen’s version 3.3 (released with WordPress 6.6), the site information links remain below the social navigation at any screen size. Before that, the social navigation had displayed after the site information on larger screens, which created a mismatch between the visual order and the Document Object Model (DOM) order.

Site, Privacy Policy, and Proudly powered by WordPress links appear beneath three social icon links in the site footer
The two footer elements are stacked, now at screen widths larger than 910 pixels.

If you would like to have the two elements side-by-side, with the social navigation first, you could paste styles in a child themeChild theme A Child Theme is a customized theme based upon a Parent Theme. It’s considered best practice to create a child theme if you want to modify the CSS of your theme. https://developer.wordpress.org/themes/advanced-topics/child-themes/. or in the Customizer’s Additional CSS panel.

Check the instructions on how to do this
@media screen and (min-width: 56.875em) {
	  1. Reset the social navigation width.
	  2. Adjust margins to place site info along the right edge.
	.site-footer .social-navigation {
		width: auto;
		margin: 0.538461538em auto 0.538461538em 0;
	.site-info {
		margin: 0;

	/* Reverse the margins for right-to-left languages. */
	.rtl .site-footer .social-navigation {
		margin: 0;
	.rtl .site-info {
		margin: 0.538461538em auto 0.538461538em 0;
Three social icon links appear on the left side of the site footer, but Site, Privacy Policy, and Proudly powered by WordPress links are on the right.
Custom CSSCSS Cascading Style Sheets. could place the site information links on the right side.

See #60496 for more details.


Default length of time for comment author cookies has changed

[58401] changed the default length of time for comment author cookies from 0.95129375951 of a year to 1 year by taking advantage of the YEAR_IN_SECONDS constant. The comment_cookie_lifetime filterFilter Filters are one of the two types of Hooks https://codex.wordpress.org/Plugin_API/Hooks. They provide a way for functions to modify data of other functions. They are the counterpart to Actions. Unlike Actions, filters are meant to work in an isolated manner, and should never have side effects such as affecting global variables and output. can still be used to change this value.

See #61421 for more details.


Site Editor Patterns on Classic Themes

#61109 now directs a classic theme’s Appearance > Patterns menu to the site editor Patterns view (/wp-admin/site-editor.php?path=/patterns), providing a consistent pattern and template management experience regardless of theme type. For themes with block-template-parts support, the Appearance > Template Parts menu has been removed, with template parts now accessible under the site editor’s Patterns > Template Parts view.

Fluid Typography

Some theme.json presets require custom logic to generate their values, for example, when converting font size preset values to clamp() values.

The custom logic is handled by callback functions defined against the value_func key in WP_Theme_JSON::PRESETS_METADATA. The callback functions are invoked in WP_Theme_JSON::get_settings_values_by_slug().

In WordPress 6.6, settings of the current WP_Theme_JSON instance, are now passed to these callback functions. The permits callback functions to return values that rely on other settings in the theme.jsonJSON JSON, or JavaScript Object Notation, is a minimal, readable format for structuring data. It is used primarily to transmit data between a server and web application, as an alternative to XML. tree.

In the case of font sizes presets, it fixes a bug whereby the callback function — wp_get_typography_font_size_value() — was not taking into account settings values passed directly to the WP_Theme_JSON class.

External libraries

jQuery UIUI User interface library update

The jQuery UI library was updated to version 1.13.3. For more information on the changes included, see jQuery UI 1.13.3 release notes.

Login and Registration

New array arguments for wp_login_form

The wp_login_form() function has two new array arguments: required_username and required_password. Passing true to these arguments adds the ‘required’ attribute to the input fields.

$args = array(
    'required_username' => true,
    'required_password' => true,
wp_login_form( $args );

There is no change to the default field output.

See #60062 for more details.

Multisitemultisite Used to describe a WordPress installation with a network of multiple blogs, grouped by sites. This installation type has shared users tables, and creates separate database tables for each blog (wp_posts becomes wp_0_posts). See also network, blog, site

Custom ports for multisite site addresses

#21077 made it possible to install and operate a Multisite installation on a host name that includes a port number, and the corresponding #52088 added full support for this to the local development environment. This means it’s now possible to run Multisite on an address such as localhost:8889.

Update enabled mime types for new multisite installs

In #53167, the list of mime types that are enabled for upload were aligned to those enabled by regular sites by switching from a hard-coded list of types (that had become outdated) to using coreCore Core is the set of software required to run WordPress. The Core Development Team builds WordPress.’s get_allowed_mime_types function. This ensures that new multisite installs are up to date with the current mime types supported in core, including the recently enabled image/webp and image/avif types.

Note that, since this is only used to populate the schema for new networks, it will only affect newly created multisite networks – it does not change the allowed mime types for existing networks. To adjust the mime types allowed for existing sites, developers can continue to use an approach as follows for filtering the upload_filetypes option:

Script Loader

Obsolete polyfills dependencies have been removed

In [57981], now obsolete polyfills such as wp-polyfill, wp-polyfill-inert and regenerator-runtime were removed from the react script dependency in WordPress, as they are no longer needed in modern browsers supported by WordPress. Developers relying on wp-polyfill need to manually add it as a dependency to their scripts.

See #60962 for more details.

Script modules can now be used in the WordPress adminadmin (and super admin)

With #61086, script modules can now be used in the WordPress admin. Before WordPress 6.6, script modules were only available on the front end.


Search has a much later priority

In [58215], the search input on the front-end admin bar is added at a different priority. It was previously inserted at priority 4 and then floated to appear at the end of the admin bar. It is now inserted at priority 9999 to load at the end of the admin bar without CSS manipulation.

Extenders placing admin bar nodes after the search or replacing core search should take the new priority into consideration.

Example: Assign different priority based on WordPress version

$priority = ( version_compare( $GLOBALS['wp_version'], '6.6-alpha', '>=' ) ) ? 4 : 9999;
add_action( 'admin_bar_menu', 'wpadmin_toolbar_test_link', $priority );
 * Add a node to the WP admin toolbar.
 * @param object $wp_admin_bar WP Admin Bar object.
function wpadmin_toolbar_test_link( $wp_admin_bar ) {
			'parent' => 'top-secondary',
			'id'     => 'mylink',
			'href'   => '#',
			'title'  => __( 'My Link' ),

See #60685 for more details.

Props to @swissspidy, @jorbin, @johnbillion, @audrasjb, @joedolson, @ironprogrammer, @ramonopoly, @jonsurrell, @sabernhardt, @jdy68, @afercia and @juanmaguitar for their contribution and/or reviews.

#6-6, #dev-notes, #dev-notes-6-6