WordPress background updates fail to update automatically

Time to visit your sites and the and press the update button.

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.

https://wordpress.org/news/2018/02/wordpress-4-9-4-maintenance-release/