Kubuntu 19.04 Disco Dingo was released on April 18, 2019 with 9 months support. As of January 23, 2020, 19.04 reaches ‘end of life’. No more package updates will be accepted to 19.04, and it will be archived to old-releases.ubuntu.com in the coming weeks.

The official end of life announcement for Ubuntu as a whole can be found here [1].

Kubuntu 19.10 Eoan Ermine continues to be supported, receiving security and high-impact bugfix updates until July 2020.

Users of 19.04 can follow the Kubuntu 19.04 to 19.10 Upgrade [2] instructions.

Should for some reason your upgrade be delayed, and you find that the 18.10 repositories have been archived to old-releases.ubuntu.com, instructions to perform a EOL Upgrade can be found on the Ubuntu wiki [3].

Thank you for using Kubuntu 19.04 Disco Dingo.

The Kubuntu team.

[1] – https://lists.ubuntu.com/archives/ubuntu-announce/2020-January/000252.html
[2] – https://help.ubuntu.com/community/EoanUpgrades/Kubuntu
[3] – https://help.ubuntu.com/community/EOLUpgrades