Home > Hardware > Macintosh

Computerworld - As expected, Apple opened the download gate for iOS 4 today shortly after 1 p.m. Eastern time, 10 a.m. Pacific time.

The mobile operating system upgrade appeared to download and install with few problems, although some users complained that backups of their iPhones were taking much longer than usual.

Downloads initiated by Computerworld staffers immediately upon the 1 p.m. Eastern time launch took approximately 19 minutes to complete, while users on Apple's iPhone support forum reported total upgrade times -- including downloading the update, backing up their iPhones and restoring them with the new operating system -- that ranged from 20 minutes to over an hour. The iOS 4 update weighed in at almost 580MB.

However, some iPhone owners encountered problems in the backup portion of the process.

"Stuck in 'back up' mode for 20 minutes so far -- no visible progress," said a user identified as "sclntx" on the Apple support forum at 2:12 p.m. Eastern time. "Arrrgggghhhh."

"It looks as though it is sitting at the backup part, even though I synced and backed up before hitting the update button," said "scsutke92" on a discussion thread dedicated to the problem.

"The Backup is 'glacial' slow but it is doing it," assured another user, identified as "Nik Green," in a second support forum thread.

Other users reported different difficulties with the upgrade.

"I downloaded iOS 4.0 and it didn't install, then it went into recovery mode," said a user called "sohailkhan1993" on Monday. "Every time I connect it to iTunes it doesn't come out of recovery mode, [so] I click on Restore and it attempts this but a message comes up 'The iPhone could not be restored. An unknown error occurred (21).'"

An Apple support document dated May 2 spells out error messages users may see when they try to update and restore their iPhones, iPod Touches and iPads.

The iOS 4 upgrade can be installed on 2008's iPhone 3G and second-generation iPod Touch, and 2009's iPhone 3GS and third-generation iPod Touch. The new operating system is not available for the first-generation iPhone or iPod Touch, both of which debuted in 2007.

Previously, Apple has charged iPod Touch owners $9.95 for major operating system upgrades, but an accounting change last year now allows it to provide iOS 4 for the iPod Touch at no charge.

Apple claims that iOS 4, which was previewed in April, boasts more than 100 new features, including multitasking, folders and enhanced enterprise tools.

Users can download iOS 4 by connecting an iPhone or iPod Touch to a PC or Mac, running iTunes, clicking on the device in the listing on the left and then clicking the "Check for Update" button.

The new version of the operating system is set to ship for the iPad this fall, according to previous statements by Apple. The company has not disclosed a specific launch date for the tablet's upgrade, however.

Although iOS 4 undoubtedly includes several security patches, Apple had not released an advisory detailing the number and severity of the vulnerabilities it addressed by 3 p.m. Eastern time. Assuming Apple publishes an advisory later today, it would appear here, on the company's support site.

Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, or subscribe to Gregg's RSS feed . His e-mail address is gkeizer@ix.netcom.com.

Read more about Macintosh in Computerworld's Macintosh Topic Center.