Only a day after WordPress 4.9.3 was released, it released 4.9.4 version to fix a critical bug that broke the automatic update mechanism in WordPress.
Last week, WordPress released a 4.9.3 version with patches for a total of 34 vulnerabilities. But unfortunately, a bug went unnoticed during the 4.9.3 development cycle which triggers a PHP Fatal error when WordPress tries to update itself automatically.
Explaining about the bug WordPress lead developer Dion Hulse said:
“#43103-core aimed to reduce the number of API calls which get made when the auto-update cron task is run. Unfortunately, due to human error, the final commit didn’t have the intended effect and instead triggers a fatal error as not all of the dependencies of find_core_auto_update() are met. For whatever reason, the fatal error was not discovered before 4.9.3’s release—it was a few hours after release when discovered.”
However, a few hours after the 4.9.3 version release, the WordPress team discovered the bug and issued a fix in the WordPress 4.9.4 version.
But the WordPress administrators who have the 4.9.3 version need to manually install the 4.9.4 version update by themselves for now.
There are several ways in order to manually install the update.
- WordPress administrators can sign into their accounts, Dashboard→Updates and then click “Update Now”.
- Through command line, use the ‘wp core update’ command to get the update ( if WordPress and WP-CLI installed previously).
- To manually install the update by FTP, download the latest ZIP and upload it to your site using FTP. Only the
wp-includes/update.php&wp-includes/version.phpfiles are expected to change.
Make sure you have the WordPress 4.9.4 version after the installation.
However, it seems that the bug was limited to only a few websites, as few users found both the updates (4.9.3 and 4.9.4) automatically installed.
Share your experience in the comments if you had to manually install the fix.