Android Question New 9.3 - Switch to Android X - class file for not found

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Licensed User
Hello all,

I apologize for having to raise this issue again, but unfortunately the answers
I've found in the forum given have not helped me :( .

I have made a new installation as described online for B4A 9.3 and made
those steps for switching to Android X. But unfortunately I can't get my
projects compiled.

B4A Version: 9.30
Java Version: 8
Parse den Code.    (0.15s)
Building folders structure.    (0.01s)
Kompiliere den Code.    (0.76s)
Kompiliere Layoutcode.    (0.11s)
Organisiere Libraries.    (0.00s)
    (AndroidX SDK)
Generiere R Datei.    (0.48s)
Kompiliere Debugger-Code    (2.54s)
Kompiliere generierten Java Code.    Error
B4A line: 428
javac 1.8.0_221
src\de\apsdelta\android\apprm602\ error: cannot access PagerAdapter
  class file for not found

What have I tried so far:
- Android SDK in B4A - checked that I have all downloads.
- Jetifier says: Nothing to do (I had already run that).
- Clean Project.
- Tried multiple suggestions with #AdditionalJar to add support-v4.jar.
- Searched for which was not installed
and downloaded this among other matching "".

Unfortunately, all this did not change the error message.

I'm sure I miss something and I'm the one not getting it. I mean it lacks
a reference or a lib but I do not know where to start anymore.

Any help or tip would be great!



Licensed User
Hello Erel,

I apologize for the late reply. I was at least a few days on vacation.

Where is AHPageViewer library located? Open the internal libraries folder and make sure that it is NOT there.
Darn :eek:. AHPageViewer was indeed in the internal libraries folder (with 4 others).

Moved to correct position and compiled afterwards without problems with AndroidX.

My mistake, thank you very much for the help!



Licensed User
Goodmornig, i'm having theh same problem. After upgrading to B4A 10.70
Followed these instructions:

B4A – The simple way to develop native Android apps (

To get rid of this error:

Linking resources Error
unknown option '-A'.
aapt2 link [options] -o arg --manifest arg files...
My app relies on AHViewPager.
- if the " internal libraries folder " is @ "Anywhere Software\Basic4android\Libraries" then there are no 'AHViewPager' files located in the folder
Please advice
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