Welcome to WordPress 5.1 ~ A Little Better Every Day

Site Health

With security and speed in mind, this release introduces WordPress’s first Site Health features. WordPress will start showing notices to administrators of sites that run long-outdated versions of PHP, which is the programming language that powers WordPress.

When installing new plugins, WordPress’s Site Health features will check whether a plugin requires a version of PHP incompatible with your site. If so, WordPress will prevent you from installing that plugin.

Learn more about updating PHP

Editor Performance

Introduced in WordPress 5.0, the new Block Editor continues to improve. Most significantly, WordPress 5.1 includes solid performance improvements within the editor. The editor should feel a little quicker to start, and typing should feel smoother. Nevertheless, expect more performance improvements in the next releases.

Multisite Metadata

5.1 introduces a new database table to store metadata associated with sites and allows for the storage of arbitrary site data relevant in a Multisite/Network context.
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Cron API

The Cron API has been updated with new functions to assist with returning data and includes new filters for modifying cron storage. Other changes in behaviour affect cron spawning on servers running FastCGI and PHP-FPM versions 7.0.16 and above.
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New JS Build Processes

WordPress 5.1 features a new JavaScript build option, following the large reorganisation of code started in the 5.0 release.
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Miscellaneous improvements include updates to values for the WP_DEBUG_LOG constant, new test config file constant in the test suite, new plugin action hooks, short-circuit filters for wp_unique_post_slug() and WP_User_Query and count_users(), a new human_readable_duration function, improved taxonomy metabox sanitisation, limited LIKE support for meta keys when using WP_Meta_Query, a new “doing it wrong” notice when registering REST API endpoints, and more!
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