WordPress Release: 4.9.3

TL;DR

WordPress 4.9.3 is a maintenance release that addresses 34 bugs across various components including the Customizer, Widgets, Media, Editor, and more. This update improves stability, fixes compatibility issues with PHP 7.2, enhances the user experience in the Customizer and Media workflows, and resolves several UI and accessibility issues. The update is recommended for all WordPress 4.9.x users.

Highlight of the Release

• Fixed compatibility issues with PHP 7.2
• Improved Customizer workflow and messaging
• Enhanced media handling including better image cropper functionality
• Fixed issues with the TinyMCE editor
• Updated Twemoji to version 2.4.0
• Improved URL handling for canonical redirects when post dates change

Migration Guide

WordPress 4.9.3 is a maintenance release and should not require any specific migration steps. The update process should be smooth for most users:

1. Back up your website before updating (always recommended)
2. Update through your WordPress dashboard or via your preferred method
3. Test your website functionality after the update

For Developers:

• If you were using JSHint in your custom code that integrated with WordPress, note that it has been replaced with esprima due to license compatibility issues
• If your code relies on counting non-countable values, be aware that fixes for PHP 7.2 compatibility may affect behavior
• If you've built custom implementations using the Customizer, review the changes to locking behavior and status handling

Upgrade Recommendations

This update is recommended for all WordPress 4.9.x users. WordPress 4.9.3 contains numerous bug fixes and enhancements that improve stability, compatibility with PHP 7.2, and the overall user experience.

The update addresses issues that could affect editing content, customizing your site, and working with media. It also includes performance optimizations that reduce unnecessary API calls.

As with any WordPress update, it's always a good practice to back up your site before updating. Most users should experience a smooth update process with no issues.

Bug Fixes

• Widgets:

  • Prevented checkValidity from running on a form when a widget is first added to sidebar (#43003)
  • Allowed relative/partial URLs in Image Widget's link field (#42740)
  • Ensured media is explicitly enqueued from Text widget when Media widgets are unregistered (#43125)

• Customizer:

  • Improved accuracy of messages displayed when accessing Customizer with already published or trashed changesets (#42497)
  • Prevented SFTP theme installation notification in multisite when user cannot install themes (#42674)
  • Used changeset-specific "locked" messages when branching is enabled (#42655)
  • Prevented frontend previewing from causing a customization lock on the changeset (#42975)
  • Set default status for Customizer to draft if user does not have capability to publish (#42686)
  • Ensured customize_autosaved requests only use revision of logged-in user (#42450)
  • Included nav menu item for Home custom link in search results for "Home" (#42991)
  • Ensured heartbeat keeps changeset locked when in branching mode (#42658)
  • Corrected "Add Items" button reference in help text shown after creating a new menu (#42565)

• Editor:

  • Changed the test in user_can_richedit() to detect when IE11 is in compatibility mode (#42503)
  • Fixed toolbar drop-downs by applying overflow style on the actual element with text (#43090)
  • Fixed issue with keeping scroll position by treating all shortcodes as preview-able (#42908)
  • Backported bug fixes to TinyMCE components (#42722)

• Media:

  • Restored white background of the content area in media modal (#43088)
  • Fixed page scrolling when opening the media modal (#39859)
  • Stored and reused image cropper ratio settings if available (#42646)

• PHP 7.2 Compatibility:

  • Fixed warning on counting non-countable values (#42860)

• REST API:

  • Added existing term_id to the error data object when attempting to create a duplicate term (#42597)

• Updates:

  • Optimized Background Update processes to only trigger during core update checks when an autoupdate is available (#43103)

• Email:

  • Fixed notifications for site or network admin email address changes (#42693)

• Other:

  • Used PCRE syntax compatible with older PCRE versions in WPDB (#43109)
  • Fixed issue in postMessage events handler by checking for message object existence (#43005)
  • Made install_languages capability check less restrictive (#42697)

New Features

• Improved URL Handling: Added support for redirecting to the correct URL when a post date changes, similar to how WordPress handles slug changes.
• Enhanced Media Playback: Introduced a custom error handler for MediaElement.js to display a download link if FLV files cannot be rendered.
• Code Editor Search Improvements: Added Ctrl/Cmd+F as aliases for persistent search in the Code Editor for more intuitive behavior.
• Playlist API: Exposed a new wp.playlist.initialize() API to allow for better handling of media playlists after selective refresh in the Customizer.

Security Updates

No specific security fixes were mentioned in this release. However, as with all WordPress updates, it's recommended to keep your installation up to date to benefit from the latest security improvements.

Performance Improvements

• API Calls Optimization: Reduced the number of API calls to api.wordpress.org during release windows by only triggering Background Update processes when a core autoupdate is available.

• Cache Improvements: Increased the cache period for plugin and theme checks when running via cron from never-cache to 2 hours, reducing unnecessary API calls.

• Media Modal: Improved the media modal behavior to avoid unnecessary page scrolling, providing a smoother user experience.

Impact Summary

WordPress 4.9.3 is a maintenance release that focuses on bug fixes and enhancements across multiple components. The update addresses 34 issues, with significant improvements to the Customizer, Widgets, Media handling, and Editor functionality.

Key impacts include:

1. Improved stability and compatibility: Fixed issues with PHP 7.2 compatibility and addressed various bugs that could affect site functionality.

2. Enhanced user experience: Improved workflows in the Customizer with better messaging and locking behavior, fixed media modal issues, and enhanced the image cropper functionality.

3. Performance optimizations: Reduced unnecessary API calls to WordPress.org servers during update checks, which helps decrease server load during release windows.

4. Better content editing: Fixed several issues in the TinyMCE editor that could affect content formatting and the handling of shortcodes.

5. URL handling improvements: Added support for redirecting to the correct URL when post dates change, improving SEO and user experience.

The update is relatively minor in terms of new features but addresses important bugs and compatibility issues that could affect day-to-day WordPress usage. Site administrators should update to benefit from these improvements and ensure continued compatibility with modern PHP versions.