Ubuntu Studio 19.04 was released on April 18, 2019. As a non-LTS release, 19.04 has a 9-month support cycle, and, as such, the support period is now nearing its end and Ubuntu Studio 19.04 will reach end of life on Thursday, January 23, 2020.
The supported upgrade path from Ubuntu Studio 19.04 is via Ubuntu Studio 19.10. Instructions and caveats for the upgrade may be found at:
If you’re still running Ubuntu Studio 19.04 (Disco Dingo) you need to upgrade to 19.10 as soon as possible in order to continue receiving updates. Failure to upgrade to Ubuntu Studio 19.10 from 19.04 may result in the inability to upgrade at all or require using difficult upgrading techniques.