Ubuntu releases and LTS

Ubuntu publishes a new release every six months. Every two years, the April release is a Long Term Support release, usually called LTS.

For a server, use a supported LTS release unless you have a clear reason not to. You get a longer standard-support window, fewer major upgrades, and documentation that remains useful for longer.

Interim releases contain newer software, but their support window is much shorter. They make sense when you need a specific kernel, driver, or package version and you are ready to upgrade the machine again soon.

Check the release you are running

Use the release file instead of guessing from a screenshot or tutorial:

cat /etc/os-release

Look for VERSION_ID and VERSION_CODENAME:

VERSION_ID="24.04"
VERSION_CODENAME=noble

The codename appears in repository names and support documentation. Commands written for another Ubuntu release may install a different package version or use a configuration layout your system does not have.

Package updates are not release upgrades

sudo apt upgrade updates packages inside the current Ubuntu release. It does not move a 24.04 system to a later Ubuntu release.

A release upgrade uses do-release-upgrade. It is an operational change: read the new release notes, update the current system, confirm free disk space, back up important data, and plan downtime before starting.

LTS systems normally upgrade to the next LTS in sequence. Do not assume you can skip several releases.

Check support before following old instructions

An old tutorial can look correct while pointing at an unsupported repository. Before copying commands, confirm:

• your Ubuntu release is still supported
• the instructions name your release or codename
• the package source is still maintained
• you have a recovery path if the change fails

Try this: run cat /etc/os-release on one Linux machine. Record its version, codename, and whether it is an LTS release.