Last checked and updated on 09 Jun 2026
What Is New in WordPress 5.9
WordPress 5.9, "Joséphine", is a major release focused on the Site Editor, block themes, and design tools. It fundamentally changes how you build and design sites with full-site editing.
| Category | Key Changes |
|---|---|
| New Features | Full Site Editor, Twenty Twenty-Two Theme, Navigation Block, Block-based Widgets Editor |
| Design Tools | Global Styles, Style Book, Block Gap Support, Duotone Filters |
| Improvements | List View, Pattern Transformations, Image Block Lightbox, PHP 8.0+ Compatibility |
| Performance | Lazy-Loading for iframes, Caching for Global Styles & Block Patterns |
What is the Full Site Editor?
The Full Site Editor (FSE) is the flagship feature of WordPress 5.9. It provides a centralized interface for editing every part of your site-templates, headers, footers, and more-using blocks.
In practice, this means you're no longer confined to the post editor. You can visually design your entire site structure from the Site Editor, making it a massive leap towards a truly block-based WordPress.
How do Global Styles work?
Global Styles decouple your site's design from its content. You define a color palette, typography settings, and spacing defaults that are automatically applied across all blocks and templates.
This matters because it brings a design system approach to WordPress. Changing your brand's primary color in one place instantly updates it everywhere, eliminating the need for repetitive custom CSS.
What's new for theme developers?
WordPress 5.9 introduces block themes, which are built specifically for the Full Site Editor. The new default theme, Twenty Twenty-Two, is the first official block theme.
These themes rely on a theme.json file to configure the Global Styles and settings. This file gives themes fine-grained control over which design tools are available to users, creating a more intentional editing experience.
What block improvements were made?
Several core blocks received significant upgrades. The Navigation block allows you to create and manage menus visually anywhere on the site. The List View provides a structural overview of your content, making it easier to select nested blocks.
New pattern transformations let you convert a paragraph into multiple columns or a list into a paragraph with a single click, speeding up content creation.
Were there any performance gains?
Yes, 5.9 includes under-the-hood performance enhancements. Lazy-loading for iframes improves initial page load times by deferring off-screen content.
Caching for Global Styles and block patterns reduces server load and speeds up the Site Editor interface, making the backend feel more responsive for users.
FAQ
Is the Full Site Editor stable for production sites?
While powerful, the Site Editor in 5.9 is a first-generation tool. It's stable for use with block themes like Twenty Twenty-Two, but expect a learning curve and some limitations compared to traditional theme development.
Do I have to use a block theme with WordPress 5.9?
No, the update is backward compatible. Classic themes will continue to work exactly as before, and you can still use the Customizer. The new features are primarily activated when using a block theme.
How does the new Navigation block differ from the old menus?
The old menu system was separate from the block editor. The new Navigation block is a core block that can be placed anywhere and edited visually within the Site or Post editor, offering more flexibility and control.
What's the purpose of the theme.json file?
The theme.json file is a configuration file for block themes. It centralizes theme settings like color palettes, typography, and spacing, and allows theme authors to control which design options are available in the editor.
Has PHP 8.x compatibility been addressed?
WordPress 5.9 continues to improve compatibility with PHP 8.0 and 8.1 by cleaning up deprecated code and warnings. It's a step towards full support, but always test your code and plugins on the new PHP versions before upgrading.