On February 6, 2018 WordPress.org released version 4.9.4 of the WordPress software. This comes quickly on the heels of the Feb 5 release of version 4.9.3.
The February 5 release contained a major bug found immediately after it was pushed live. The latest version, 4.9.4. will need to be manually updated in the dashboard. It will encounter an error if it tries to auto-update. (Valet clients will have this taken care of for them during their regular software and security checks each week.)
Here is an excerpt from the text of the release notes for version 4.9.4, published February 6, 2018 on the WordPress.org blog:
“This maintenance release fixes a severe bug in 4.9.3, which will cause sites that support automatic background updates to fail to update automatically, and will require action from you (or your host) for it to be updated to 4.9.4.
Four years ago with WordPress 3.7 “Basie”, we added the ability for WordPress to self-update, keeping your website secure and bug-free, even when you weren’t available to do it yourself. For four years it’s helped keep millions of installs updated with very few issues over that time. Unfortunately yesterdays 4.9.3 release contained a severe bug which was only discovered after release. The bug will cause WordPress to encounter an error when it attempts to update itself to WordPress 4.9.4, and will require an update to be performed through the WordPress dashboard or hosts update tools.
WordPress managed hosting companies who install updates automatically for their customers can install the update as normal, and we’ll be working with other hosts to ensure that as many customers of theirs who can be automatically updated to WordPress 4.9.4 can be.