Hello,
I’m using aCalendar to.schedule my calendar events and that worked really fine until the update of my FP4 to Android 15.
Now notifications of scheduled events don’t show up or show up very late (20-25 min after the should have shown up).
I’ve already checked the permissions and the app already has permission to run in background.
Does anybody could help me to solve this issue?
After running some checks, I’m seeing something similar with Etar. One test entry was OK, another notification arrived 12 min. late.
As may be expected, this is probably a system bug and not linked to a specific app.
Did you disable battery optimization for the app?
As far as I know this is now the permission to run in background or am I wrong? The app is allowed to run in background, yes.
Settings > Apps > [your app] > App battery usage > Allow background usage
Also enabled in my case.
For those using cloud-connected calendars on multiple devices, it’s important to remember that the connecting middleware such as DAVx5 also needs to run in the background.
That was also already the case on my phone. But I decided to toggle the permission off then on, without actually launching the app.
A few minutes later the calendar on device B finally received an entry that had been registered in the cloud data hours before and created on device A hours earlier still.
Any developer knows that unfortunately parameter values shown in the UI don’t always reflect the values implemented by software. It’s sometimes useful to rewrite key parameters in the context of a software malfunction.
When you tap on “Allow background usage” (not the slider beside it) you should reach another menu where you can select “optimized” or “unlimited”. Maybe it’s worth a test to select “unlimited” there…
I think I’ve already tested that but I’ve reinstalled aCalendar because I missed many appointments.
I’ve now setted the option and will try to see if this changes something (tbh it seams that the reinstall made things better but not solved the problem completely).
Will report here, thanks for all your ideas and help 
Yes, I already had that set for the calendar, but not for DAVx5.
This kind of problem is a devil to test but I’ll try to keep an eye on it!
Unfortunately the problem persists: I had no problems during the day but in the evening three events were not notificated…
To me this seams connected somehow with Android 15, I know someone that has the same problems on a FP 5.
I think this is a wrong implementation on the app side. Scheduled alarms work flawlessly for iunrestricted apps; Android 15 is Now Rolling Out to Fairphone 4! 📲 (FP4.QREL.15.14.3.20250923) - #201 by peci1
I have the same problem with Business Caledar and Google calendar. I have been through all of the optimisation stuff. I don’t get an alert apart from less than 1% of the time. It posts a new sort of slider of events all the time on the activity screen where it shows what is going to happen but does not send any alerts. To be honest it makes the phone almost useless as I miss appointment alerts all the time, causing unecessary grief. How can this be escalated? I’ve searched for solutions with Business Calendar and they are unfamiliar with it. Is there a way to get someone who can do something about this, to do so?
I only can add that the situation has not changed until now - the calendar reminders don’t work very often.
What I saw is that the app “Tasks” always can show up the reminders at the correct time - aCalendar can’t….
I’ve noticed the same problem. Using acalendar+ and davx5. Both apps can run in background. It is very annoying.
Fairphone 4 with Android 15.
Perhaps you can try the calendar app Etar. You can find it on F-Droid and on Play store.
I have good experience with it.
Etar is open source.