Canonical has announced that Ubuntu 19.04 ‘Disco Dingo’ will reach its end-of-life on January 23, 2020. If you’re still using this version of Ubuntu, which was released last April, you’ll want to make sure you upgrade before the deadline in order to keep getting new security updates. Upgrading Ubuntu isn’t too difficult, you just need to head to the update manager and follow the instructions after pressing upgrade.
Canonical provides detailed upgrade instructions but to summarise, ensure that you’ve applied any available patches, then read the Ubuntu 19.10 release notes for any issues that could occur. While the upgrade should be available from the update manager, you may need to press Settings inside the update manager and ensure ‘Notify me of a new Ubuntu version:’ is set to ‘For any new version’, you can find that setting in the Updates sub-menu.
For most people, Ubuntu LTS (Long Term Support) releases are best to use because they are the most stable and receive updates for at least five years. Non-LTS versions like Ubuntu 19.04 are stable too but only receive updates for nine months and act as a sort of testing ground for new features before they’re introduced into the next LTS release which businesses and other formal users tend to opt for.
The next LTS, Ubuntu 20.04 ‘Focal Fossa’, is due for release on April 23 with a release candidate dropping on April 16 and the beta arriving on April 2. A few months after Ubuntu 20.04 is released, Canonical will push the first point release, at which time, Ubuntu 18.04 LTS users will be notified that an upgrade is available. Waiting until the first point release gives Canonical time to receive bug reports and issue patches.