iOS 8 upgrades have spiked in the last month, likely thanks to iPhone and iPad sales and upgrades over the December holiday break, new figures published by Apple show.
About 68 percent of all compatible iPhones and iPads are now running Apple's latest mobile operating system released in mid-September, the company's developer pages say.
Just weeks after its debut in September, less than half of all iOS 8-compatible devices were running the latest software and adoption appeared to be stalling, with an increase of only 1 percentage point in three weeks.
Many couldn't upgrade even if they tried. Because the update was significantly larger in storage space than expected, in order to upgrade, many had to delete apps, photos, or other content from their devices.
The iPhone and iPad maker faces a class-action suit for alleged "deceptive and misleading" marketing over device storage space.
Apple says on its developer pages that it measures its operating system share from App Store visits over a period of time. Figures are typically released every two or three weeks.