I recently worked with a client who runs a pretty intense photography marketplace. He’s the type who likes to live on the edge, so he was running a pre-release version of WordPress to get a head start on some new block features. One morning, I get a frantic Slack message: “Ahmad, I can’t publish anything. The button is there, but nothing happens.” Total nightmare. After digging through the console and tracing the hooks, I realized it wasn’t his custom code. It was a core bug involving hidden async-upload fields being marked as ‘required,’ effectively killing the publishing flow. These are the exact issues being squashed in the latest WordPress 6.9 core updates.
You see, I initially thought I could just write a quick filter to bypass the validation on those fields. Classic dev move. Try to patch the symptom instead of the cause. But then I realized that messing with core field requirements in the REST API during a version transition is like playing Jenga with a toddler. The real solution wasn’t a hack; it was making sure we tracked the progress of the release candidate. If you’re following the source at make.wordpress.org/core/2025/12/01/wordpress-6-9-release-candidate-4/, you’ll see RC4 addresses this specifically under ticket #64305.
Squashing Critical Bugs with WordPress 6.9 Core Updates
One of the quietest but most dangerous fixes in this release involves _wp_cron(). If your site uses ALTERNATE_WP_CRON, there was a nasty bug where running cron during the shutdown hook would actually break the site. For high-traffic WooCommerce stores, that’s a death sentence for scheduled emails and inventory syncs. Trust me on this: you don’t want to find that out on production.
/**
* A safer way to ensure your custom tasks are hooked correctly
* until the core fix is fully rolled out.
*/
function bbioon_check_cron_compatibility() {
if ( defined( 'ALTERNATE_WP_CRON' ) && ALTERNATE_WP_CRON ) {
// Log or handle specific logic for high-traffic environments
error_log( 'BBIOON: Monitoring alternate cron behavior.' );
}
}
add_action( 'init', 'bbioon_check_cron_compatibility' );Another major win in RC4 is the fix for REST API error handling. Previously, updating a non-existent setting would return a ‘success’ status. That’s a massive headache for headless WordPress setups or anyone relying on robust API integrations. It’s these small, technical details that separate a “functional” site from a professional-grade platform. The full list of changes can be found in the official WordPress core blog, but these highlights are what will save your skin during the next update cycle.
So, What’s the Real Takeaway?
The lesson is simple: don’t sleep on the Release Candidates, but for heaven’s sake, don’t test them on your live money-maker. WordPress 6.9 is shaping up to be a solid release, especially with the added ability to hide blocks, but it requires a disciplined testing process. If you aren’t using a staging environment or the WordPress Playground to vet these changes, you’re just asking for an emergency weekend call. Period.
Look, this stuff gets complicated fast. If you’re tired of debugging someone else’s mess and just want your site to work, drop my team a line. We’ve probably seen it before.
Are you still manually patching core bugs, or are you ready to upgrade your testing workflow?
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