Apple released iOS 9 today at 1 p.m. ET, but in the first hour users reported that they were unable to grab the 1GB download.
[ Related: 7 tips and tricks for iOS 9 ]
"Software Update Failed," the message read on iPhones and iPads. "An error occurred downloading iOS 9." Computerworld confirmed the problem, initially seeing it on multiple iOS 8 devices. But after several subsequent attempts, the download successfully started about an hour after Apple issued the upgrade.
Similar reports of early problems were posted on Apple's own support forums and elsewhere on the Internet. "Not a very helpful error," wrote someone identified as "yanic" on the former.
Others countered with snark. "Strangely, this is not a 'limited time offer,' said "stedman 1" on the same thread, likely referring to Microsoft's Windows 10 free upgrade offer, which is valid for one year. "The software will be available tomorrow, and the next day, and next week."
Some advice ended up being more helpful. "You are facing an overloaded server which is pretty typical of the first day a software revision comes out," contended "Ralph Landry1" on a different discussion thread.
Several iPhone owners who had said that they were unable to download iOS 9 returned to the same forum threads to report they had gotten the upgrade later.
Apple's track record with iOS releases has been mixed. Last year's iOS 8 roll-out seemingly started off smoothly -- there were few initial complaints about getting the upgrade -- but many soon griped that 8's large size forced them to wipe apps and content from their devices before they could install the new OS.
iOS 9's size and the free space requirements for installation were both reduced to address that problem of last year. The free space demand for iOS 9 fell to 1.3GB to 1.8GB from last year's 4.5GB to 5GB.
Apple also botched the iOS 8.0.1 update a week after iOS 8's original release, and was forced to pull it from its servers almost as soon as it was posted because of a bug that crippled cellular connections to the then-new iPhone 6 and iPhone 6 Plus.
iOS 9, which will be pre-loaded on the new iPhone 6S and iPhone 6S Plus that Apple will start selling on Sept. 25, is a free upgrade for owners of the iPhone 4S, iPhone 5, iPhone 5C, iPhone 5S, iPhone 6 and iPhone 6 Plus; iPad 2, the third- and fourth-generation iPads with Retina screens, the iPad Air and Air 2, the iPad Mini, and the iPad Mini 2 and 3 with Retina; and the fifth-generation iPod Touch.
Apple introduced iOS 9 at its annual developers conference in June, when CEO Tim Cook and other executives highlighted new features -- particularly for the latest iPad -- and a more intelligent Siri assistant.
Today, Computerworld reviewer Michael deAgonia concluded that iOS 9, although primarily a performance and stability upgrade, was "a clear winner" for newer iOS devices and surprisingly fluid on older iPhones.
"iPad users, especially those with newer iPads, should consider iOS 9 a must-have update, as it unlocks multitasking features that power users have wanted," deAgonia added.
Apple also patched 102 security vulnerabilities with iOS 9.
iOS 9 can be downloaded over the air from iPhones, iPads, and iPod Touches, or through iTunes. From an iPhone, for instance, users must touch the "Settings" icon, then the "General" button on the resulting screen. Tapping "Software Update" will kick off the process.
This story, "Apple releases iOS 9 as early download attempts fail" was originally published by Computerworld.