Apple's new look operating system got off to a rocky start as users complained about difficulties downloading it.
Hailed as a new beginning for the technology giant, the iOS 7 was eagerly anticipated but tech fans complained of messages telling them: "An error occurred whilst downloading iOS 7.0".
Users took to social media such as Twitter to express their frustration at the setback as "iOS 7.0" became a trending topic. Some had managed to download the system and praised it.
Industry observers had suggested the arrival of iOS 7, which is said to have a cleaner look than its predecessors, could go some way to silencing Apple's critics.
It was unveiled just months after Apple posted its first profit slide in a decade and drew accusations that it has failed to innovate.
British design chief Sir Jonathan Ive introduced the operating system as an ''important new direction'' when he showcased the software at Apple's annual Worldwide Developers Conference in San Francisco earlier this year.
The American company's CEO Tim Cook described it as ''the biggest change to iOS since the introduction of the iPhone''.
It has been designed to make the iPhone appear bigger, with features crafted to take advantage of the entire screen.
Text is said to appear sharper, while a ''control centre'' on the phone allows users to adjust settings with just one swipe from the bottom of the screen.
This gives instant access to functions such as airplane mode, wi-fi, bluetooth or do not disturb, and enables users to quickly pause or play a song, jump to the next track and stream music.