Ubuntu 14.04 (codenamed Trusty Tahr) was released five years ago (in April of 2014). As a long-term support (LTS) release, that means it was eligible to receive bug fix and security updates for five years. As of April 30, 2019, the standard support period will end, and you will no longer be able to download updates from archive.ubuntu.com.

For the typical user (like us), this means:

• No security fixes. No package updates. No new kernels. That’s the end.
• The packages will, at some point, be removed from archive.ubuntu.com, and archived at old-releases.ubuntu.com.

When the files are archived, that also means that you can no longer upgrade using the do-release-upgrade command. The only “official” remedy is to reinstall. There is an “unofficial” community-authored method for upgrading via old-releases.ubuntu.com, but I have not tested this with Trusty.

If you run 14.04 in a business environment and are unable to update or redeploy for awhile, you can purchase limited additional support from Canonical (the company that provides commercial support for Ubuntu). Starting with 12.04, Canonical began providing critical security fixes beyond “end-of-life” for LTS releases, through a program called “Extended Security Maintenance”. You can find more information about ESM here.