iOS 5 was previewed on June 6, 2011 during WWDC 2011. At the same event, Apple previewed Mac OS X Lion[2] and announced its cloud-based media service, iCloud.[3] For the second time, support for some devices was dropped, specifically the iPhone 3G and the iPod Touch (2nd generation). Supported devices on this release include the iPhone 3GS onwards, the iPod Touch (3rd generation) onwards, and the original iPad onwards.[4]
On October 4, 2011, Apple held an event at the 4 Infinite Loop building at its headquarters in Cupertino, California. While other items were discussed, the main focus was the unveiling of the iPhone 4S and its new, exclusive Siri software.[5] The release date for iOS 5, October 12, was announced at this event.[4]
The iPhone 4S came with iOS 5 pre-installed, but older units required the update to be installed through iTunes.[6] However, when the update was first released, many users received error messages upon attempting to download it, and some had warnings that their devices could not be restored. It was thought that Apple's servers were simply not able to keep up with the demand, causing as many as half of the initial requests for the update to fail