Cwa-app-android: Negative value of the counter for how long the app has been active

[1ukast]

Avoid duplicates

• [x] Bug is not mentioned in the FAQ
• [x] Bug is specific for Android only, for general issues / questions that apply to iOS and Android please raise them in the documentation repository
• [x] Bug is not already reported in another issue

Describe the bug

The green risk indicator box in the app reads "-5 von 14 Tagen aktiv" (-5 of 14 days active).

Expected behaviour

The number of days that the app has been active cannot be below zero.

Steps to reproduce the issue

1. I have downloaded the app at the release date.
2. I have switched off "Risiko-Ermittlung" as well as bluetooth and GPS on that same day.
3. I reactivated all of the above on 5th of July, 2020.
4. When opening the app, the negative counter occurs (Even after restarting the app or disabling and enabling "Risiko-Ermittlung" again).

Technical details

• Mobile device: Samsung SM-J530F
• Android version: 9
• App Version 1.0.4

Possible Fix

Additional context

• I have never changed any date or time settings on my phone during the last months.

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Internal Tracking ID: EXPOSUREAPP-1844

[1ukast]

[Update:]

When checking existing issues, i was searching for other entries that mentioned negative numbers.
Now I just found this entry in the FAQ: https://www.coronawarn.app/en/faq/#days_active_Android

If someone can confirm that this is the same problem, the issue can be closed i guess.

[jkrwdf]

The issue #796 linked in the FAQ deals with a rounding effect which causes the days counter to increase unexpectedly slow.

According to my understanding of the algorithm, I think this rounding effect cannot cause the number to become negative, so I recommend not to close this issue yet and give the maintainers a chance to assess it.

[tkowark]

Thanks for reporting the issue. The value turning negative really seems to be a different bug than just a rounding error and should not really happen. The team will have a look.

[AlexanderAlferov]

@1ukast thank you for your input!

I tried to reproduce this issue, but could not see negative value.

Please, kindly share some more details:
1) Did you switch off "Risiko-Ermittlung", bluetooth and GPS after on-boarding process? Or before application main screen was shown?
3) Did you kill the application after first start? Or may be you just have used "Close all apps" button.
2) Did you turn on all the above before application start on 5th of July?

Thank you!

Best regards,
Alex

[1ukast]

Unfortunately, I do not remember every detail.
But yes, I think I started the app at least once when bluetooth and GPS was disabled.
I often close all apps with the "Alle schließen" button. But I have not killed the application with the "Stopp erzwingen" button in the system settings or something similar.

If i remember correctly, I was not connected to any network when I opened the app yesterday (July 5th) after this long period without using the app. Since the application was complaining about a missing network connection, I was enabling mobile data then.

Is there any way that I can help you by reading out some data from my application?
Should I try if the bug persists after a reboot of the system or do I risk loosing information that could be relevant to identify/fix the bug?

Best regards.

[pwoessner]

Hi @1ukast
A reboot of you phone will not cause a loss of data in the app, so you can try that one. The only thing that you only should do as a last solution is reinstalling the app, since this will delete the tracing data if that is the only tracing app installed on your device (e.g. if you have installed SwissCovid or Immuni).

Have you manually changed the device date & time at some point in time?

Thanks,
Philipp

Edit: just read your additional info that you never changed your time settings. We will look into the issue but for the time being we cannot identify any steps to reproduce your issue/how this can happen with the current calculation logic.
Can you also please give an update what your current number of days is?

[1ukast]

Hi,

my current number of days is still -5 of 14.
I rebooted the device today and it didn't change anything.

As written above, I have not changed any date&time settings before the error occured.
However, just now I was trying to play with setting different dates to see the result:

Setting it to days in the past:

• any day from June 29th until today: Counter remains at -5
• Setting it to June 28th: Counter is at -6
• Setting it to June 27th: Counter is at -7
• Setting it to June 26th: Counter is at -8
• ...
• Setting it to June 20th: Counter is at -14
• ...
• Setting it to June 17th: Counter is at -17
• Setting it to June 16th: Counter shows -18 for a few milliseconds after opening the app, then the box turns grey and reads "Unbekanntes Risiko - Da Sie die Risiko-Ermittlung noch nicht lange genug aktiviert haben, konnten ....."

Until this point, the numbers above were reproducable when changing the date back and forth. Then I tried days in the future:

• Setting it to July 13th: Counter remains at -5
• Setting it to July 30th: Counter hits 14/14

From now on, I can't get any negative numbers anymore by changing the date.

[Edit:] Obviously my current number is not -5 anymore as written in the first line. But it was -5 before playing with the date settings. Now it is 14/14.

[mDeisen]

Hi,

I encountered the same problem when switching to and back from the SwissCovid app.

Currently the counter shows -35 out of the last 14 days.
This roughly fits with decrementing one for every day that the app was inactive (due to usage of the SwissCovid app).
Before the switch, the app was active for longer than 14 days and the counter was behaving normally.
Updating the app, restarting or switching back and forth between SwissCovid and Corona Warn does not change anything about the counter (It might increment by 1/day again if i switch back to Corona Warn).

Currently I expect it to keep decrementing with every day I keep using the SwissCovid app -> I will give an update on this.

Mobile device: Samsung SM-G986B/DS
Android version: 10
App Version 1.2.1

Best Regards.

[darkdragon-001]

Same problem here. My usage so far:

• Install the app and run it for 4 days for testing.
  -> correct count increasing daily
• Turn it off and turn Austrian app on
  -> correct count stays constant
• After about 10 days, turn Austrian app off and CWA on
  -> wrong count does not increase
• Turn CWA off after two days
  -> wrong count is at -1 10 days later

[pwoessner]

Hi all,
thanks for your details and your updates. With your input we managed to identified the issue and will fix it in an upcoming version.

Technical background: We are storing the time intervals (point in time when you deactivated it _from_ and point in time when you activated it _to_) of the time when tracing is deactivated to calculate the tracing time. More details about the calculation can be found here: https://github.com/corona-warn-app/cwa-app-android/issues/796#issuecomment-652381709
We only delete an interval when the point in time of to is no longer in the past 14 days. This leads to an issue with periods where the app is deactivated for a long amount of time and the from timestamp is no longer in the last 14 days but the to timestamp is still in that last 14 days time period. In that case we take the complete duration of the deactivated time instead of the corrected duration (from should be max the point in time --> today - 14 days).

This leads to the issue that when tracing is deactivated for example for 20 days, we calculate the active tracing times like this: 14 possible days - 20 inactive days = - 6.