Mozilla will start a more aggressive campaign to convince users of the older Firefox 3.6 to upgrade to the newest edition, Firefox 7.
The move would be the first time that Mozilla has offered what it calls an "advertised update" or a "major update" to people still running 2010's Firefox 3.6. Earlier this week, Mozilla said it would kick off the offer today.
According to Mozilla, the offer does not hint at an impending retirement of the older version.
"The advertised update has no bearing on support levels [emphasis in original]," said Firefox release manager Christian Legnitto in a blog post Wednesday. "It does not mean Firefox 3.6 is end-of-life."
The offer that users see starting today will ask them to upgrade to the newest edition, Firefox 7.0.1. If they decline, they can continue to run Firefox 3.6 and will keep receiving the security updates Mozilla has releases every six weeks.
Firefox 3.6, however, may be on the chopping block soon. Under a plan Mozilla is now weighing, the company would retire Firefox 3.6 and discontinue security updates in the first quarter of 2012.
That proposal, dubbed "Extended Support Release," or ESR, would slow down Firefox's rapid-release schedule for enterprise users, who have been critical of the fast upgrade tempo Mozilla kicked off last spring.
Legnitto made it clear that the Firefox 3.6-to-Firefox 7 update offer was simply business as usual. "We did this for [Firefox] 3.0.x -> 3.5, 3.5.x -> 3.6, 3.6.x -> 4.0 and 3.6.x -> 5.0... nothing new [emphasis in original]," said Legnitto.
Legnitto also said that based on similar offers in the past, Mozilla expects "to see a significant percentage of users installing the new version."
According to Web metrics firm Net Applications, Firefox 3.6 accounted for about 28% of all copies of Mozilla's browser that were used during September, making it the second-most-popular edition behind Firefox 6.
At 4 p.m. ET, a Mozilla spokeswoman said that the Firefox 3.6 major upgrade offer had been delayed, but she did not say when it would commence.