Thank you, Wordfence for giving everyone one the heads up about a serious problem with WordPress Auto Update.

If I understand it correctly, if you have WordPress 4.9.3 and update to 4.9.4, it will work, but any future update will have to be done manually.

“WordPress has included the capability to auto-update since WP version 3.7, which was released four years ago. The WordPress auto-update function only updates minor versions by default. That means that only releases that change the number to the far right of your WP version will auto-update. In other words, if you were on 4.9.3 and 4.9.4 is released, your site will auto-update. But If WordPress 5.0.0 is released, your site will not auto-update by default.”

This will not affect everyone, happily; only those sites which have been manually upgraded in the last three months. Unmaintained sites may not be affected. The problem being, though, that they MIGHT. You could be stuck on 4.9.3 for years before you think to check and then you will have to manually update at that time.

What to do? Check your WordPress version now. Bring it up to 4.9.4. And then check it again next month and the month after that. You should (or someone should) be checking for updates a minimum of every month anyway. Thanks again to Wordfence for the heads up. You can read the whole article here.