WordPress Release: 5.9.3

TL;DR

WordPress 5.9.3 is a maintenance release that addresses several important bugs and performance issues. It optimizes editor preloading, fixes issues with block themes, improves media gallery functionality, and enhances compatibility with modern SSH configurations. This update focuses on improving the block editor experience and fixing issues that affect site editors, developers, and administrators working with the new block theme system introduced in WordPress 5.9.

Highlight of the Release

• Optimized preload paths for post and site editors to improve performance
• Fixed get_post_galleries() to only return gallery content
• Added support for modern SSH public key algorithms (ssh-ed25519)
• Fixed issues with block themes and customizer integration
• Improved handling of block support styles and asset URLs

Migration Guide

No specific migration steps are required for this maintenance release. The changes are primarily bug fixes and performance improvements that should work seamlessly after updating.

If you're using WordPress with a custom installation path (WordPress core outside of the regular directory), this update will fix issues with broken asset URLs for newer blocks, which may have been causing display problems with block themes.

For developers using SSH for file uploads on systems with OpenSSH 8.8+, this update adds support for the ssh-ed25519 algorithm, which should resolve any upload issues experienced after the deprecation of ssh-rsa.

Upgrade Recommendations

This is a recommended update for all WordPress 5.9.x users, especially those:

1. Using block themes or the site editor
2. Experiencing performance issues with the block editor
3. Using WordPress with a custom installation path
4. Managing sites on servers with modern OpenSSH configurations (8.8+)

As this is a maintenance release focused on bug fixes and performance improvements, it's considered low-risk and should be applied promptly to ensure optimal site performance and functionality.

Bug Fixes

Editor Fixes

• Fixed broken asset URLs for newer blocks (like the navigation block in the 2022 theme) when WordPress core is installed outside of the regular directory.
• Changed the use of uniqid() to wp_unique_id() for generating CSS class names, improving reliability and security.
• Modified the location of block support styles in wp_head for better rendering.

Block Theme Improvements

• Fixed an undefined variable warning thrown when duotone color setting was set to null in Block Themes theme.json file.
• Prevented the Customizer/Live Preview button from showing for installed block themes on the theme installation page.
• Improved menu order handling for the Widgets menu when using block themes with declared Widgets support.

Media Functionality

• Fixed get_post_galleries() to ensure it only returns gallery content, addressing an issue where non-gallery block content was incorrectly included in the results.

New Features

Enhanced Customizer Experience for Block Themes

• Added an informational notice in the Customizer when a block theme is active, encouraging users to use the Site Editor for the best full site customization experience.

Improved SSH Compatibility

• Added support for the ssh-ed25519 public key signature algorithm as an alternative to ssh-rsa, ensuring compatibility with modern OpenSSH configurations (8.8+) where ssh-rsa is disabled by default.

Security Updates

No specific security fixes were mentioned in this release. However, the change from uniqid() to wp_unique_id() for generating CSS class names improves the predictability and security of generated identifiers, and the addition of support for the ssh-ed25519 public key algorithm enhances security for file uploads on systems with modern SSH configurations.

Performance Improvements

Editor Performance Optimization

• Optimized preload paths in post and site editors to match actual requests:
  • Removed the / preload as the payload is very large and not needed on any critical path
  • Modified the preloaded path for /wp/v2/taxonomies to correspond to what loadTaxonomyEntities requests
  • Updated the /wp/v2/users/me path to match the real request (without query parameters)
  • Added preloading of /wp/v2/settings for the post editor (already present in site editor) as it's requested on the critical path during editor boot

These optimizations ensure that only necessary resources are preloaded, reducing initial load time and improving editor startup performance.

Impact Summary

WordPress 5.9.3 is a targeted maintenance release that addresses several important issues affecting the block editor experience and block theme functionality. The most significant improvements include optimized preloading for better editor performance, fixed asset URLs when WordPress is installed in non-standard directories, and improved SSH compatibility for file uploads on modern systems.

For site editors and content creators, the editor optimizations will result in faster loading times and a smoother editing experience. Developers will benefit from fixed asset paths and better handling of unique IDs. Administrators managing sites with block themes will see improved integration between themes and the customizer.

This release demonstrates WordPress's continued refinement of the Full Site Editing experience introduced in version 5.9, addressing edge cases and improving performance without introducing breaking changes. The fixes for SSH compatibility also ensure WordPress remains functional on servers with modern security configurations.