Besides Firefox 12, which launched Tuesday, users can also turn to Firefox Extended Support Release (ESR), the build that Mozilla crafted to soothe customers, including IT administrators who manage Firefox for their workers, who were unhappy with the every-six-week upgrade cadence of the standard browser.
The current version of Firefox ESR is based on Firefox 10, which shipped in December 2011. ESR receives only security updates during its 54-week lifespan. Except for the patches, Firefox ESR won't change until November 2012, and will be supported with updates until early February 2013.
If users want to keep Firefox 3.6, they must disable updates before the May auto-upgrade. On Windows, that setting is reached by selecting "Options" from the Firefox menu, then "Options" again (on the Mac, "Preferences" from the Firefox menu), clicking the "Updates" tab, then choosing "Never check for updates."
"Users will be automatically updated unless they have specifically disabled updates," said Keybl in an email reply to questions. "However, we strongly advise our users to upgrade from Firefox 3.6, as they will no longer receive critical security updates."
Firefox 3.6 users will soon see this notice, which tells them that their browser will automatically be upgraded to Firefox 12.
In May 2011, Mozilla automatically upgraded Firefox 3.5 to Firefox 3.6 after the former was retired from support, the first time it had used the tactic to rub out an aged browser. It worked: Firefox 3.5's share fell dramatically.
But Mozilla isn't the only browser maker to now use automatic upgrading: Last December, Microsoft announced it would automatically upgrade Internet Explorer (IE) to the newest browser suitable for each version of Windows without asking users for approval. Conceivably, the IE auto-upgrade could put an end to IE6, the nearly-11-year-old browser that Microsoft has been trying to bury for years.
IE's automatic upgrading has kicked off in Brazil and Australia; Microsoft will expand it worldwide this year.
Firefox 3.6 accounted for a significant chunk of Mozilla's usage share last month. By metrics company Net Applications' estimates, 13% of all copies of Firefox, or about one-in-eight, were version 3.6.