Apple users with iOS 3.1.3 haven't been able to use Apple's App Store or update their existing apps.

Agitated users have taken to Apple forums to air complaints.

Well there have been enough reports and posts here to conclude that this is indeed an Apple problem with their Appstore. All we need now is for media outlets to get a hold of this information, so they can get the news of this failure out to the public. Once that happens then Apple is bound to get moving on fixing their problems. Until then we will all have to wait, wrote users Mr. Interested on the Apple forum under the thread App download buttons not working.

The problem isn't confined to the U.S. either, apparently. It impacts iPhone, and iPod Touch users with iOS 3.1.3.

Same problem with iPhone 3G and iOS3.1.3 in Europe. I think that the APpStore doesn't work anymore in our firmware 3.1.x.

Impacted users haven't been able to update existing iPhone or iPod Touch apps or download new ones since a December 16 software update was issued by Apple. The problem is that Apple support has told users to update their operating system to iOS 4 or iOS 5. PC Mag reports, however, that many of these users have the original iPhone or first-generation iPod touch, neither of which support iOS 4. To get iOS 5, meanwhile, users need an iPhone 3GS, iPhone 4, or iPhone 4S.

Others, meanwhile, are restricted to iOS 3 by their places of work or preference.

Wrote a user on the Apple forum: I know...upgrade to OS 4.x....I would but everything I read says that the phone is basically useless after the upgrade as everything is too slooooooooow.

Apple has not yet publicly acknowledged the issue, and didn't respond immediately to a request for comment.