Cwa-app-ios: Dead man notification does not work

[databus23]

Avoid duplicates

• [x] Bug is not mentioned in the FAQ
• [x] Bug is not already reported in another issue

Describe the bug

As reported previously background checks are ~not working on my iPhone~ only work when I connect my phone to a charger for unknown reasons.
So I was patently waiting for the new dead man notification that was added with 1.3.0. Unfortunately I received no notification within 43 hours (at which point I opened the app to force a check).

Expected behaviour

After 36 hours of no check a local notification should prompt me to open the app.

Steps to reproduce the issue

Wait for 36 hours after the last check without opening the app.

Technical details

• iOS Version: 13.7
• Device: iPhone 8 Plus

Possible Fix

I have no idea really but I'm wondering if the local notification is only scheduled in an actual background task, not when the check is executed while the app is in the foreground. Because in my case the checks are only happening when I'm opening the app.

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Internal Tracking ID: EXPOSUREAPP-2994

[Marco2907]

Hi @databus23 , thanks for sharing your content. Could you wait another 30 hours for a return time and then check the time of the risk calculation?

Thanks,
MP

Corona-Warn-App Open Source Team

[databus23]

@Marco2907 Not sure I fully understand. What do you mean be a "return time"? By "check the time of the risk calculation" you mean the last time a check was logged in Settings-> Exposure notifications?

[thomasaugsten]

This is also difficult to test the notification check at the moment only for the background task and not the risk calculation. This means if the background task was startet but canceled without a successful risk calculation the notification will be rescheduled. We plan to extend this to the risk calculation.

[databus23]

@thomasaugsten Not sure I fully understand, but this sounds like my assumption was correct that the dead man notification only works if the background task was executed previously.

[thomasaugsten]

No this means every time the background task was executed the notification is rescheduled in 36h. But an executed background task doesn't mean a successful risk calculation because iOS can stop the background task after 1sec because of memory or battery issues and this means the risk calculation is also stopped.

[databus23]

I see, so this could be the problem in my case.

[mss1010]

Is there any news on this? I also have the case now, that after more than 36 hours there was no background check and no notification.

iPhoneXS
newest iOS and app version

[thomasaugsten]

This will be improved in v1.5

[mss1010]

This will be improved in v1.5

Thanks for the fast reply! Can you give an estimation when 1.5 will be released? I think 1.4 was planned for mid october.

[thomasaugsten]

Not yet there is already an internal planning but not yet ready to publish.

[Ein-Tim]

@databus23
Can you please check if the Dead Man Notification now works with Version 1.5.1 (or above) from CWA?

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I can confirm that the notification is working for me 👍

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Edit: I think this Issue can be closed since Dead Man Notifications are working with 1.5.1 and above (@heinezen could you close it)

[heinezen]

Should be fixed in https://github.com/corona-warn-app/cwa-app-android/pull/1513 and release 1.7.

Edit: Sorry for the mixup, this PR was the fix for Android. The Dead Man Notification bug on iOS is currently investigated.

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Corona-Warn-App Open Source Team

[databus23]

I can't really reproduce the issue anymore as the background task execution started to work somewhat reliable for me.

[Ein-Tim]

@heinezen Please leave this Issue open.
With the (buggy) release of 1.6.0 and the (not optimal) hotfix 1.6.1 there are some users who complain about not working Dead Man Notifications (f.e.: https://github.com/corona-warn-app/cwa-app-ios/issues/916#issuecomment-727920973).

I can also confirm what @PalminX stated in #916:

The last check on my phone was performed at 15.11. at 22:42. Until now, no new check happened (only a failed one) and also no Dead Man Notification.

[heinezen]

@Ein-Tim We will leave it open until 1.7 has been rolled out to all users and check for feedback.

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Corona-Warn-App Open Source Team

[PalminX]

No deadman notification showed up for me, up to 65 hrs after the laste foreground check. Then, another background check happened (see https://github.com/corona-warn-app/cwa-app-ios/issues/916#issuecomment-728935091)

[PalminX]

@Ein-Tim We will leave it open until 1.7 has been rolled out to all users and check for feedback.

Corona-Warn-App Open Source Team

Is this fix also for iOS? Asking since the PR was for the Android repo: https://github.com/corona-warn-app/cwa-app-android/pull/1513

[heinezen]

@PalminX

Is this fix also for iOS?

Apologies, I have confused the fixes for the different apps. I've updated my initial post.

The Dead Man Notification Bug for iOS is currently being investigated and there are unfortunately no updates on this.

Sorry for the confusion,
CH

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Corona-Warn-App Open Source Team

[Ein-Tim]

Can anybody here report a working dead man notification with 1.6.0 or above?

[dsarkar]

Hi @PalminX,

FYI, I have added your report to the internal ticket for the developers.

Best wishes,
DS

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Corona-Warn-App Open Source Team

[PalminX]

I received a dead-man notification yesterday, Nov 19, at 21:!5, exactly 40 hrs after the last logged background check (which was at 5:15 on Nov 18).

[ndegendogo]

Well - seems not reliably. I got none, see details here

[dsarkar]

Dear @ndegendogo, @PalminX,

Many thanks for feedback, we forward these observation to the developers!

Best wishes,
DS

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Corona-Warn-App Open Source Team

[ndegendogo]

@dsarkar I am a bit confused now - the PR you mentioned is for Android but this ticket is in the iOS repo?

[Ein-Tim]

Can anybody confrim that Dead man notificaitons are working with 1.7.1?
Or are the background checks to reliable with this version? 😉

[ndegendogo]

@dsarkar maybe the devs could confirm that there is a related PR also for iOS?

Two weeks ago they were still investigating - but that comment might well be outdated today.

In the first week of 1.7.1 my checks were perfect. Now since two days they start to have large gaps, yesterday it was 8 hours instead of 4, today I had a gap of 12h. Still by far better than before 1.7.1.

I'll continue to watch.

[dsarkar]

Dear @ndegendogo,

There is no PR that correlates directly to a fix of the deadman issue. However, this problem is understood to have resolved by fixing other issues.

Related internal tickets: EXPOSUREAPP-3880, EXPOSUREAPP-3821.

Let's monitor for the moment, any feedback will be forwarded to the developers! Many thanks,

Best wishes,
DS

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Corona-Warn-App Open Source Team

[dsarkar]

@ndegendogo, I got some feedback, which might explain some recent irregularities in the checks. In den night from Sunday to Monday and Monday to Tuesday, time 0100 - 0200, the server was prepared for ENF v2 (future CWA version 1.8). Possibly, checks in that time frame were skipped.

Best wishes,
DS

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Corona-Warn-App Open Source Team

[ndegendogo]

Thanks @dsarkar.

I am just preparing to submit another ticket on some of the irregularities I saw last Thursday. (Nothing very serious, but it would be interesting if there is an explanation).

[dsarkar]

@ndegendogo, sure, see https://github.com/corona-warn-app/cwa-app-ios/issues/1631#issuecomment-739326690. Best, DS

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Corona-Warn-App Open Source Team

[Ein-Tim]

Did some additional testing, Dead Man notifications are working with 1.7.1 👍

[ndegendogo]

@Ein-Tim wow - so you saw such a notification? 🎉🎉

[dsarkar]

@Ein-Tim, thanks for letting us know. Could you let us know, how you could trigger such notifications? In any case, we will forward this information to the developers.

We will close this issue now. However, re-open if appropriate. Thanks to everybody for contributing here.

Best wishes,
DS

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Corona-Warn-App Open Source Team

[Ein-Tim]

@ndegendogo

wow - so you saw such a notification?

Yes, this one:

@dsarkar

Could you let us know, how you could trigger such notifications?

Yeah, just make sure that your phone is not connected to the Internet for a bit more than 36h and you will recive one. 👍

But I saw that it was not exactly 36h after the last check, more like 37 1/2h. But I think this is ok 👍

[dsarkar]

@Ein-Tim, thanks for the information, very much appreciated. We will forward your observation to them and we would suggest closing this issue after monitoring a few more days. Best wishes,
DS

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Corona-Warn-App Open Source Team

[dsarkar]

Dear @Ein-Tim, @ndegendogo, @databus23, @PalminX, and community,

Thank you for your contributions. This issue will be closed now. Please, re-open if necessary.

Best wishes,
DS

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Corona-Warn-App Open Source Team