Android Question Incompatibility with Android11

[Angelo Maradini]

I would like to install in Android 11 an app realized with B4A last year.
When I install the app from apk, I receive a message like this: " This app was built for an older version of Android and may not work properly. Try checking for updates, or contact the developer."
so I set in manifest targetSdkVersion="29"
AddManifestText(<uses-sdk android:minSdkVersion="14" android:targetSdkVersion="29"/> ... )
in this way I could install the app, the message disappears but the app can't run. a white screen appears and disappears suddenly
could someone help me please?

 

[mcqueccu]

Not enough information.

What does the app do?
Are you loading the layout?

 

[Angelo Maradini]

if I install the same apk in android10 it works, the problem is in Android11
the first page contains some buttons and images

 

[Star-Dust]

Surely it accesses resources that are no longer available on SDK 29 and crashes.

This App maybe accesses the root external memory?

 

[josejad]

Can you run B4A-Bridge in the phone with Android 11 and run the app in debug mode to check the logs?

 

[agraham]

Probably due to permissions or new privacy limitations in Android 11
(1) android.jar / targetSdkVersion / minSdkVersion | B4X Programming Forum

 

[Angelo Maradini]

In debug I see the wrong line is this:
File.Copy(File.DirAssets, vFileName, File.DirDefaultExternal, vFileName)

I can't copy a file and the error in log is
java.io.FileNotFoundException: /storage/emulated/0/Android/data/com.company/files/FileName.db: open failed: ENOENT (No such file or directory)

this happens only in android 11, not in Android 10...

 

[DonManfred]

ExternalStorage - Access SD cards and USB sticks

Before we start: External storage means a real sd card or a connected mass storage USB device. This class can also be used to access the secondary storage (File.DirRootExternal). This becomes relevant with newer versions of Android that restrict direct access. It has nothing to do with runtime...

www.b4x.com

 

[agraham]

File.DirDefaultExternal

Is the problem. You need to request storage permission and add the manifest entry for for targeting SDK 29 which is in the link I gave you above.

Sorry! I sloppily assumed it was File.DirRootExternal instead of reading it carefully.

 

[MbedAndroid]

i thought copying a file from assets to dirinternal is also not possible with sdk30.

 

[Erel]

i thought copying a file from assets to dirinternal is also not possible with sdk30.

No such restriction.

 

[Angelo Maradini]

I haven't yet solved this bug. someone could help me,please? any ideas?

 

[josejad]

someone could help me,please?

Upload a small project that shows the problem, it will be easier to help you.

 

[MbedAndroid]

manifest: check

SetApplicationAttribute(android:requestLegacyExternalStorage, true)

AddManifestText(<uses-permission

   android:name="android.permission.WRITE_EXTERNAL_STORAGE"

   android:maxSdkVersion="19" />)

in b4a code check or add

    If Sys.SDK>22 Then

        rp.CheckAndRequest(rp.PERMISSION_WRITE_EXTERNAL_STORAGE)
        Wait For Activity_PermissionResult (Permission As String, rresult As Boolean)
        If rresult Then
            .............
            
            End If
        End If

this is working on android11. There are many examples on the forum

 

[Mahares]

File.Copy(File.DirAssets, vFileName, File.DirDefaultExternal, vFileName)

This line:

File.Copy(File.DirAssets, vFileName, File.DirDefaultExternal, vFileName)

should be:

File.Copy(File.DirAssets, vFileName, rp.GetSafeDirDefaultExternal(""), vFileName)  'need rp as runtimepermissions lib

It works with SDK 30 and device running OS 11.

i thought copying a file from assets to dirinternal is also not possible with sdk30.

Why are you making such incorrect statement. We are already all confused with all these new permissions maze and you add another cork to it.

 

[MbedAndroid]

Why are you making such incorrect statement. We are already all confused with all these new permissions maze and you add another cork to it.

well i tried it once, and didnt worked on android 11. I couldnt copy a manual into file.internal. So i said "thought".

But to sort things out, i tried it again, and now without issues. Dont know why it didnt worked out first time.

 

[Angelo Maradini]

Thanks at all, in particular to Mahares!
I have solved changing
File.DirDefaultExternal
with
rp.GetSafeDirDefaultExternal("")
Good job!!!