Reports of problems with the iOS 5 upgrade flooded Apple's support forum today.
It's unclear why users are not able to upgrade, but the snafu may be due to swamped servers on Apple's end.
Users said they encountered installation errors near the tail end of the installation process, after iTunes downloaded the update and backed up the device.
iPhone and iPad owners reported a variety of error messages, and many said they had tried to upgrade to iOS 5 multiple times, from different computers running iTunes and to numerous devices, all without success.
"I have two iPads, and two iPhone 3GS. All are coming up with same error on three different machines," said a user identified only as "Garyuk" on one of several quickly-growing threads on Apple's "Using iPhone" support forum. "One Windows machine and two Mac's and all are getting same error. I think [iOS 5] is flawed and there is something very seriously wrong with the code or the way it tries to wipe and restore."
Apple first offered iOS 5 on its download servers at around 1 p.m. ET.
Some believe that the problem is on Apple's end -- possibly due to overloaded servers -- because the error messages pop up at the point where iTunes tries to connect with Apple.
"To anyone getting 'An internal error occurred (3200)' while installing iOS 5.0, Apple's servers are swamped, and failing half the requests," said Jay Freeman on Twitter
Freeman is a noted iOS "jailbreaker" and the developer behind Cydia, a tool that lets owners of hacked iPhones find and install apps not authorized by Apple.
Suggestions abounded on Apple's support forum about how to sidestep the errors and complete the upgrade, ranging from switching off the Mac's or Windows PC's firewall to deleting the existing backup.
In some cases, users said such suggestions had worked for them, but just as many -- if not more -- reported that they had not.
A few people claimed that their attempts to upgrade to iOS 5 had "bricked" their iPhones, making them unusable.
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Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at @gkeizer, on Google+ or subscribe to Gregg's RSS feed . His e-mail address is email@example.com.