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Troubleshooting

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 Discord, it is usually helpful to include this full log, e.g. via 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

or:

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

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   _python_bundle          menu.kv   private.mp3       widgets.pyo
editor.pyo            interpreter.pyo  libpymodules.so         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.

The python installation, along with all side-packages, is mostly contained inside the _python_bundle folder.

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 setup.py, 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=python3,kivy. This also applies when using buildozer, in which case add python3 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.

Errors related to Java version

The errors listed below are related to Java version mismatch, it should be fixed by installing Java 8.

  • java.lang.UnsupportedClassVersionError: com/android/dx/command/Main
  • java.lang.NoClassDefFoundError: sun/misc/BASE64Encoder
  • java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema

On Ubuntu fix it my making sure only the openjdk-8-jdk package is installed:

apt remove --purge openjdk-*-jdk
apt install openjdk-8-jdk

In the similar fashion for macOS you need to install the java8 package:

brew cask install java8
export JAVA_HOME=/Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home

Error: Cask 'java8' is unavailable: No Cask with this name exists

In order to install Java 8 on macOS you may need extra steps:

brew tap homebrew/cask-versions
brew cask install homebrew/cask-versions/adoptopenjdk8
export JAVA_HOME=/Library/Java/JavaVirtualMachines/adoptopenjdk-8.jdk/Contents/Home

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

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

Requested API target 19 is not available, install it with the SDK android tool

This means that your SDK is missing the required platform tools. You need to install the platforms;android-19 package in your SDK, using the android or sdkmanager tools (depending on SDK version).

If using buildozer this should be done automatically, but as a workaround you can run these from ~/.buildozer/android/platform/android-sdk-20/tools/android.

ModuleNotFoundError: No module named '_ctypes'

You do not have the libffi headers available to python-for-android, so you need to install them. On Ubuntu and derivatives these come from the libffi-dev package.

After installing the headers, clean the build (p4a clean builds, or with buildozer delete the .buildozer directory within your app directory) and run python-for-android again.

SSLError("Can't connect to HTTPS URL because the SSL module is not available.")

Your hostpython3 was compiled without SSL support. You need to install the SSL development files before rebuilding the hostpython3 recipe. On Ubuntu and derivatives these come from the libssl-dev package (then p4a clean builds, or with buildozer buildozer android clean).