If you haven’t yet updated your iPhone or iPod touch past iOS 4.2.1, you’ll likely find that alarms set within the built-in Clock app aren’t working. This happened last year, and we advised readers to delete each alarm and re-add it. However, this year, we think you should just take the plunge and update to iOS 5.

According to Engadget, it would appear that users affected by this bug haven’t updated past iOS 4.2.1. The most recent version of the iOS is iOS 5.0.1, which comes with a whole load of new features that Apple added in iOS 5, including a new notification system, iMessages, a Reminders app and more. However, if you’re rocking an iPhone 3G or second generation iPod touch, iOS 4.2.1 is the end of the line for you, as updating to iOS 5 isn’t possible. Original iPhone owners (if there are any of you left!) can rest assured that the bug doesn’t affect iOS 3.1.3.

Let us know in the comments if you’ve encountered this issue.