From Chad Horohoe on MediaWiki-announce:
It's November 2017, which means that the 1.28.x branch of MediaWiki has reached the end of its life. Lets wish it the best as it moves off to the great big code repository in the sky. All users are encouraged to upgrade to 1.29.x which is the latest stable branch.
Note: 1.30.0 should be out by the end of the month, we've already branched and are working on making sure the release is ready-to-go