The new year has started. Many iOS users woke up late, much to their surprise, because the alarm did not work.
This happened last year on the 1st January or 2nd January when many iOS users were afflicted by a bug that prevented their set alarms from actually working. Due to this bug, problems were apparent for the users who had to go to work or catch flights. The bug affected single-use alarms set on the January 1st and 2nd. Alarms that were scheduled to repeat at least once throughout the week were not affected.
Apple is claiming to have fixed this bug in iOS 5. Testing has confirmed that Apple has indeed fixed this issue in iOS 5. However, that does not include the millions of phones still stuck running old versions before iOS 5. Thus, users still running 4.2.1 need to upgrade to iOS 5.
Some iPhone 3G owners have still not upgraded and many in in the jailbreak community are possibly holding on to an older firmware with proven jailbreaks instead of upgrading.
However, upgrading your device to iOS 5 is a simple solution to fix the alarm bug.