Soon, users running Firefox 3.6.x will start being automatically upgraded to the current version 12.0 release of the open source web browser. The plan to auto-update these users has been being discussed since the end of March, when Mozilla Release Manager Alex Keybl proposed the move on a Mozilla planning discussion thread.
According to Keybl, Firefox 3.6.x users with updates enabled should start being upgraded in early May - the specific date has yet to be confirmed. The 3.6.x branch of Firefox, the first release of which arrived in January 2010, reached its end of life last week on 24 April; the last update to the 3.6 series was version 3.6.28 from early March.
For users and organisations that don't want to upgrade to version 12 of Firefox because of the Rapid Release process - which sees a new browser update every six weeks - Mozilla has an Extended Support Release (ESR) of Firefox specifically aimed at enterprises and other large organisations. The current Firefox ESR release, version 10.0.4, is based on Firefox 10.
Those who don't want to upgrade can turn off updates in Firefox - on Windows, updates can be disabled via Tools > Options > Advanced > uncheck "Firefox" under "Automatically check for updates". Mac users can access these settings from Preferences under the Firefox menu; however, some Mac OS X users will not be able to upgrade from 3.6.x as newer versions of Firefox no longer support PowerPC-based systems or version 10.4 of the operating system.
This isn't the first time that Mozilla has opted to auto-update users: a year ago the organisation decided to aggressively ended Firefox 3.5's life by using auto-update.
Note: For those who do not want to upgrade read the third paragraph which instructs you how to turn off updates in Firefox.