AlarmKit alarm occasionally fires at exactly 12:00 AM

App & System Services General
SeoulForest OP
Created Mar ’26
Replies 4
Boosts 1
Views 240
Participants 3

[FB22327481]

We are observing a rare issue where alarms scheduled using AlarmKit occasionally fire exactly at 12:00 AM, even though the alarm was scheduled for a different time.

This issue happens only for a very small number of users (for example, 1–2 users per several thousand per day), but multiple reports confirm that the alarm goes off exactly at midnight.

We also found that other developers are experiencing the same issue:

Observed behavior

For a small number of users:

  • Alarm fires at exactly 00:00 (midnight)
  • This happens even when the scheduled alarm time is something like 7:30 AM
  • Happens rarely
  • Hard to reproduce internally
  • Appears to happen only on real devices in production

Additional notes

  • We are using AlarmKit fixed schedules (not relative)
  • Dates passed to AlarmKit are correct at scheduling time
  • We do not intentionally create midnight alarms
  • Issue seems random

Question

Are there any known limitations or edge cases with AlarmKit fixed schedules that could cause alarms to fire at midnight?

For example:

  • Invalid date fallback?
  • Schedule expiration fallback?
  • Time zone changes?
  • Background refresh timing?
  • Maximum schedule window?

Any guidance would be appreciated, as this is affecting real users but is difficult to reproduce.

Replies  4
Boosts  1
Views  240
Participants  3
SeoulForest OP
Mar ’26

Please also take a look at this AlarmKit issue as well. We’re receiving a lot of user complaints about this too.

AlarmKit leaves an empty zombie Live Activity:

0
Hakoniwa OP
Mar ’26

Hi SeoulForest and everyone,

I’m joining this thread to share additional information regarding the reported issues with AlarmKit. While I don’t have a solution yet, I have both received user reports and personally experienced the same or similar behavior. The occurrence is rare (about once a month), but it happens consistently enough to be a reliability concern for an alarm-based feature.

My Implementation Context:

  • I have implemented a system that schedules approximately 60 fixed-schedule alarms.

  • The Issue: Alarms occasionally fail to trigger at the scheduled time.

  • Comparison: I set Local Notifications using the exact same date objects. These notifications arrive perfectly on time, which confirms there are no errors in the date/time logic itself.

Observed Behaviors:

  • Delayed Triggers: Alarms sometimes fire several minutes late, or in some cases, not at all for a long period.

  • Midnight Firing: I have observed instances where an alarm that failed to trigger at its scheduled time would suddenly fire around midnight (0:00).

  • App Launch Trigger: When an alarm has failed to trigger at its scheduled time, opening Apple’s native Clock app often causes it to suddenly fire (the Live Activity appears immediately).

Environment: This behavior has been consistent from iOS 26.1 through iOS 26.4.

Since the alarms do eventually fire (even if late), the alarm scheduling process itself seems to complete without any errors.

I’m not certain about the internal mechanics, but it feels as though the system might not be consistently monitoring third-party alarm schedules.

I would greatly appreciate any guidance or insights from anyone who has successfully resolved similar issues.

2
diegofromsan francisco OP
1d

Thanks for details @Hakoniwa .

I have refactored my code many times and still get users complaining about the same issue (random or midnight alarms).

There are also some people complaining that they uninstalled the app but still receive the alarms.

0
diegofromsan francisco OP
22h

Hi everyone,

Adding our experience, no fix either, but production data that may help triangulate. We've filed FB22638314 corroborating SeoulForest's FB22327481.

Context

  • Bird Rise alarm app: a new bird wakes the user up every day. AlarmKit on iOS 26.2+.

The bug:

  • The off-hours misfire rate. Across ~13,000 firings in 30 days, <0.5% of users intend evening or night alarms (84% schedule for 06:00–09:59), yet ~10–15% of actual rings land in the 21:00–01:00 window.

  • Same on iOS 26.1 through 26.5. This matches the "fires around midnight" / "fires at random times" pattern described upthread.

  • App Store reviews reporting the alarm continues to fire after the app has been uninstalled. 🤯

  • We've ruled out app-side causes: no EventKit, no server push, no app groups, no third-party schedulers; AlarmKit is the only persistent scheduling we use. Pattern looks similar to the zombie Live Activity on thread 819556.

I was never able to catch those issues on my devices.

Would appreciate any guidance from anyone who's gotten further with this.

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