OS X Mavericks' uptake slowed significantly in December, putting a crimp on Apple's plans to move customers to the new -- and free -- operating system.
Data from Web metrics company Net Applications also showed a worrisome fragmentation of the Mac operating system market, with three older editions, including 2009's OS X Snow Leopard, crowded around the 20 percent line, each accounting for between one-sixth and one-fourth of the user base.
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The slowdown in Mavericks adoption last month was in contrast to the rapid uptake in November, when the free operating system upgrade vaulted from fourth place among the various editions to first.
At the end of November, 32 percent of all Macs tracked online by Net Applications were running OS X Mavericks, a 21-point increase over the month prior. In December, Mavericks gained just 5 percentage points, climbing to a 37 percent share.
Still, Mavericks' December gain was twice that of OS X Mountain Lion in the second full month of its availability.Computerworld attributes November's huge Mavericks uptake to Apple's decision to give away OS X Mavericks.
As happened the previous month, the bulk of Mavericks' December gain came at the expense of Mountain Lion, which fell 2.5 percentage points, and Lion, which dropped 1.4 points.
OS X Snow Leopard again resisted major defections, losing just 0.7 points in December to slip to 19.5 percent of all editions. Users of Snow Leopard have stubbornly stuck with their aged operating system -- which may have already seen its final security update -- in large part because it was the last version of OS X to let them run applications compiled for the PowerPC processor. Its successor, OS X Lion, also orphaned many Macs made before 2008.
Mavericks' slowing adoption rate resulted in a cluster of editions around the 20 percent mark, with Mountain Lion accounting for 22 percent, Snow Leopard for 19.5 percent, and Lion for 16.3 percent in December.
That fragmentation -- four editions with more than 16 percent of the Mac user share -- is exactly what Apple was hoping to solve by making Mavericks free. "What's most important to us is seeing the software in the hands of as many Mac users as possible," said Craig Federighi, Apple's top software engineering executive, two months ago when he announced that Mavericks would be free.
The fragmentation issue will be long-lasting if past adoption trends are repeated. By Computerworld's calculations -- using six-month averages for each edition -- Mountain Lion will remain above 10 percent until April, Lion until May, and Snow Leopard until January 2015.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His email address is email@example.com. See more by Gregg Keizer on Computerworld.com. Read more about mac os x in Computerworld's Mac OS X Topic Center.
This story, "OS X Mavericks adoption steps on the brakes" was originally published by Computerworld.