Ubuntu 12.04 LTS (Precise Pangolin) is Canonical's sixteenth release of Ubuntu and its fourth long-term support (LTS) release, made available on schedule on 26 April 2012. It is named after the pangolin anteater. Previous LTS releases have been supported for three years for the desktop version and five years for the server version; this release was supported for five years for both versions, with support ending on 28 April 2017. Canonical continues to offer extended security maintenance to Advantage customers for an additional two years.
Changes in this release include a much faster startup time for the Ubuntu Software Center and refinements to Unity. This release also switched the default media player from Banshee back to Rhythmbox and dropped the Tomboy note-taking application and the supporting Mono framework as well. Also, the window dodge feature has been removed from the Unity launcher starting with Ubuntu 12.04.
Ubuntu 12.04 incorporated a new head-up display (HUD) feature that allows hot key searching for application menu items from the keyboard, without needing the mouse. Shuttleworth said that the HUD "will ultimately replace menus in Unity applications" but for Ubuntu 12.04 at least the menus will remain.
Ubuntu 12.04 is the first Ubuntu release shipped with IPv6 privacy extensions turned on by default. Ubuntu 11.10 already supported IPv6 on the desktop and in the installer (stateless address autoconfiguration SLAAC, stateless DHCPv6 and stateful DHCPv6).
Like previous LTS releases, 12.04 included point releases that bundled updates to shorten downloads for users installing the release later in its life-cycle. The point releases and dates were: 12.04.1 (23 August 2012), 12.04.2 (14 February 2013), 12.04.3 (scheduled for release on 22 August 2013, but actually released on 23 August 2013), 12.04.4 (6 February 2014) and 12.04.5 (7 August 2014).
Jesse Smith of DistroWatch said that many people, like he, had questioned Ubuntu's direction, including Unity, but with Ubuntu 12.04 he felt that the puzzle pieces, which individually may have been underwhelming, had come together to form a whole, clear picture. He said "Unity, though a step away from the traditional desktop, has several features which make it attractive, such as reducing mouse travel. The HUD means that newcomers can find application functionality with a quick search and more advanced users can use the HUD to quickly run menu commands from the keyboard." He wrote that Unity had grown to maturity, while indicating that he was bothered by its lack of flexibility. He did notice issues, however, especially that the HUD did not work in LibreOffice and performance in a virtual machine was unsatisfactory. He concluded that Ubuntu's overall experience was "head and shoulders above anything else in the Linux ecosystem."
Jim Lynch wrote "Ubuntu 12.04 is definitely worth an upgrade if you're running an earlier version. Unity is finally coming into its own in this release, plus there are other enhancements that make upgrading worthwhile. Ubuntu is getting better and better with each release. I was one of the Unity skeptics initially, but I've come to accept it as part of Ubuntu."
Jack Wallen of TechRepublic, who had strongly criticized early versions of Unity, said "Since Ubuntu 12.04 was released, and I migrated over from Linux Mint, I'm working much more efficiently. This isn't really so much a surprise to me, but to many of the detractors who assume Unity a very unproductive desktop ... well, I can officially say they are wrong. [...] I realize that many people out there have spurned Unity (I was one of them for a long time), but the more I use it, the more I realize that Canonical really did their homework on how to help end users more efficiently interact with their computers. Change is hard – period. For many, the idea of change is such a painful notion they wind up missing out on some incredible advancements. Unity is one such advancement."