Debug output

Add the --debug option to any python-for-android command to see full debug output including the output of all the external tools used in the compilation and packaging steps.

If reporting a problem by email or irc, it is usually helpful to include this full log, via e.g. a pastebin or Github gist.

Getting help

python-for-android is managed by the Kivy Organisation, and you can get help with any problems using the same channels as Kivy itself:

If you find a bug, you can also post an issue on the python-for-android Github page.

Debugging on Android

When a python-for-android APK doesn’t work, often the only indication that you get is that it closes. It is important to be able to find out what went wrong.

python-for-android redirects Python’s stdout and stderr to the Android logcat stream. You can see this by enabling developer mode on your Android device, enabling adb on the device, connecting it to your PC (you should see a notification that USB debugging is connected) and running adb logcat. If adb is not in your PATH, you can find it at /path/to/Android/SDK/platform-tools/adb, or access it through python-for-android with the shortcut:

python-for-android logcat


python-for-android adb logcat

Running logcat command gives a lot of information about what Android is doing. You can usually see important lines by using logcat’s built in functionality to see only lines with the python tag (or just grepping this).

When your app crashes, you’ll see the normal Python traceback here, as well as the output of any print statements etc. that your app runs. Use these to diagnose the problem just as normal.

The adb command passes its arguments straight to adb itself, so you can also do other debugging tasks such as python-for-android adb devices to get the list of connected devices.

For further information, see the Android docs on adb, and on logcat in particular.

Unpacking an APK

It is sometimes useful to unpack a pacakged APK to see what is inside, especially when debugging python-for-android itself.

APKs are just zip files, so you can extract the contents easily:

unzip YourApk.apk

At the top level, this will always contain the same set of files:

$ ls
AndroidManifest.xml  classes.dex  META-INF     res
assets               lib          YourApk.apk  resources.arsc

The Python distribution is in the assets folder:

$ cd assets
$ ls

private.mp3 is actually a tarball containing all your packaged data, and the Python distribution. Extract it:

$ tar xf private.mp3

This will reveal all the Python-related files:

$ ls
android_runnable.pyo  include          interpreter_subprocess  main.kv   pipinterface.kv   settings.pyo
assets                __init__.pyo     interpreterwrapper.pyo  main.pyo  pipinterface.pyo  utils.pyo
editor.kv             interpreter.kv   lib                     menu.kv   private.mp3       widgets.pyo
editor.pyo            interpreter.pyo         menu.pyo  settings.kv

Most of these files have been included by the user (in this case, they come from one of my own apps), the rest relate to the python distribution.

With Python 2, the Python installation can mostly be found in the lib folder. With Python 3 (using the python3crystax recipe), the Python installation can be found in a folder named crystax_python.

Common errors

The following are common problems and resolutions that users have reported.

AttributeError: ‘AnsiCodes’ object has no attribute ‘LIGHTBLUE_EX’

This occurs if your version of colorama is too low, install version 0.3.3 or higher.

If you install python-for-android with pip or via, this dependency should be taken care of automatically.

AttributeError: ‘Context’ object has no attribute ‘hostpython’

This is a known bug in some releases. To work around it, add your python requirement explicitly, e.g. --requirements=python2,kivy. This also applies when using buildozer, in which case add python2 to your buildozer.spec requirements.

linkname too long

This can happen when you try to include a very long filename, which doesn’t normally happen but can occur accidentally if the p4a directory contains a .buildozer directory that is not excluded from the build (e.g. if buildozer was previously used). Removing this directory should fix the problem, and is desirable anyway since you don’t want it in the APK.

Exception in thread “main” java.lang.UnsupportedClassVersionError: com/android/dx/command/Main : Unsupported major.minor version 52.0

This occurs due to a java version mismatch, it should be fixed by installing Java 8 (e.g. the openjdk-8-jdk package on Ubuntu).

JNI DETECTED ERROR IN APPLICATION: static jfieldID 0x0000000 not valid for class java.lang.Class<>

This error appears in the logcat log if you try to access from within the new toolchain. To fix it, change your code to reference instead.

websocket-client: if you see errors relating to ‘SSL not available’

Ensure you have the package backports.ssl-match-hostname in the buildozer requirements, since Kivy targets python 2.7.x

You may also need sslopt={“cert_reqs”: ssl.CERT_NONE} as a parameter to ws.run_forever() if you get an error relating to host verification