Thanks for the details.
Map cannot change in the middle of navigation,
only by user or when app starts and cannot find the offline map.
You can see if using an online map with the methods described above here and here.
Or the SD card was not suddenly accessible and so the app could not read the map file.
But that seems more like an Android or hardware problem.
What you have seen was probably that the offline map could not be read,
so the screen displayed empty tiles.
… and then the app switched therefore to online maps? Because at home I noticed that online maps were choosen.
If you are sure about that…
…this could happen, if you restarted the app and the offline map was not accessible.
Hi devemux ,
May there is an Option top Show in the Map Copyright the Status like on/ offline. ?
That prefent misunderstandings. I also remeber issues with older devices… too slow. Because the Maps increase due to more info are include.
And i get errors.
Cheers
Thanks for the idea, that could be possible.
So happend to me. I will watch too, if it has something to do with the reboot 
I never had this kind of issues before storage-access-framework.
Shame on Google 
It is indeed their decision to force such change on apps and users.
All known apps have similar problems, if you search their forums…
Android now grants a special permission for the apps to access files.
If it revokes this permission for its own reasons, the apps can do nothing.
The permission can only be granted again via the file opening procedure.
However it is strange, all this time I restart my devices without problems.
Here’s the case:
Last night I set the Kurviger app back to offline maps.
Today rebooted the device, Kurviger app accesses online maps again.
I guess I didn’t notice that earlier in such cases that I use an online map, because I have mostly good network coverage here in my area.
Only when I get into a dead zone, I get the white tiles on the map because the tiles along the route don’t reload fast enough.
If I know that, I can always check it from the entry on the bottom of the map (even if it’s very small).
But newcomers are not aware of this and they then unintentionally use the online maps and may also get the white tiles in the dead zones and get confused or angry.
Not so good for the Kurviger app.
Therefore, perhaps some kind of a clear indication would really make sense when an online map is used?
Perhaps it is useful to show an popup alert (which has to be confirmed), if the app switches to online map because it could not find the opened offline map files.
Is that possible?
This is strange, as I have never seen it, nor can I reproduce it.
Please use internal storage and repeat your tests.
Android does not like SD cards more and more…
In any case, this is out of app’s bounds.
Android (or device) decides to no longer grant the app permission to access a file.
App can only get a file permission, if user uses Android file manager and opens it.
There is already a message when app starts and cannot access the offline map.
Doesn’t it work with new Android restrictions? I will check it…
Sorry, not possible: Internal storage completely overfilled (that’s why I use the SD card) 
And I basically refuse to keep upgrading hardware (i.e. buying a new smartphone) as long as the old one works fine.
(Idea of having an indicator like “Caution: Online Map in use!” as we wrote above is not involved by this, or? I never saw the message you mentioned.)
App can only revert to online map when it starts and cannot read the offline map.
There is already a message at that time, but Android SAF prefers to not show it…
I will check what happened, so it will appear again.
Ich habe mein Handy (ist nur für Navigation) auf Werkszustand zurück gesetzt, seitdem verliere ich nicht mehr die Karte.
Gruß
Axel
Hallo,
hast du die Karte auch geöffnet?
Du musst die Karte öffnen oder hinzufügen, Einstellungen, Karten öffnen,Karten öffnen,die gewünschte Karte in deinem Speicher suchen und auswählen.
Grüße Uwe
Ich habe jetzt das ganze Kartenmaterial für Offline Karten von der SD Karte auf das Handy verschoben. Hatte am Wochenende keine Ausfälle und hoffe das ich das Problem damit behoben habe.
The info message (if app cannot read the map file at the start) should be back with Kurviger 1.14.16.
Google now forces apps to use SAF with specific permission for each file.
If it is lost by SD card (or OEM), the apps can do nothing, but ask it again.
(for security, Google allows user only to initiate the process)
Something strange seems to happen in your device or workflow,
as I cannot reproduce it.
Or you took out the card and open the app,
or you connected the phone with pc and open the app?
(where the card was used by the pc)
See also a related report above:
Nothing of this.
But it is not a real problem - as long I do not forget to switch to offline map.
(That’s why I asked for a warning indicator in the other thread “App: Info screen”.)
When app starts and cannot read the map file, a notification message already appears.
(and it reverts to the online map)
I have not set anything permanent on screen, as it could be annoying for the other users.