kivy web view crashing on android

[Degenerate Tech]

adb server version (41) doesn't match this client (39); killing...
* daemon started successfully
--------- beginning of system
--------- beginning of main
I/python  ( 5223): Initializing Python for Android
I/python  ( 5223): Setting additional env vars from p4a_env_vars.txt
I/python  ( 5223): Changing directory to the one provided by ANDROID_ARGUMENT
I/python  ( 5223): /data/data/org.test.web/files/app
I/python  ( 5223): Preparing to initialize python
I/python  ( 5223): _python_bundle dir exists
I/python  ( 5223): calculated paths to be...
I/python  ( 5223): /data/data/org.test.web/files/app/_python_bundle/stdlib.zip:/data/data/org.test.web/files/app/_python_bundle/modules
I/python  ( 5223): set wchar paths...
I/python  ( 5223): Initialized python
I/python  ( 5223): AND: Init threads
I/python  ( 5223): testing python print redirection
I/python  ( 5223): Android path ['.', '/data/data/org.test.web/files/app/_python_bundle/stdlib.zip', '/data/data/org.test.web/files/app/_python_bundle/modules', '/data/
data/org.test.web/files/app/_python_bundle/site-packages']
I/python  ( 5223): os.environ is environ({'PATH': '/sbin:/vendor/bin:/system/sbin:/system/bin:/system/xbin', 'ANDROID_BOOTLOGO': '1', 'ANDROID_ROOT': '/system', 'ANDROI
D_ASSETS': '/system/app', 'ANDROID_DATA': '/data', 'ANDROID_STORAGE': '/storage', 'ASEC_MOUNTPOINT': '/mnt/asec', 'LOOP_MOUNTPOINT': '/mnt/obb', 'BOOTCLASSPATH': '/syst
em/framework/core-libart.jar:/system/framework/conscrypt.jar:/system/framework/okhttp.jar:/system/framework/core-junit.jar:/system/framework/bouncycastle.jar:/system/fr
amework/ext.jar:/system/framework/framework.jar:/system/framework/telephony-common.jar:/system/framework/voip-common.jar:/system/framework/ims-common.jar:/system/framew
ork/mms-common.jar:/system/framework/android.policy.jar:/system/framework/apache-xml.jar:/system/framework/mediatek-common.jar:/system/framework/mediatek-framework.jar:
/system/framework/mediatek-telephony-common.jar', 'SYSTEMSERVERCLASSPATH': '/system/framework/services.jar:/system/framework/ethernet-service.jar:/system/framework/wifi
-service.jar', 'USBOTG_STORAGE': '/storage/usbotg', 'LD_PRELOAD': 'libdirect-coredump.so', 'EXTERNAL_STORAGE': '/storage/emulated/legacy', 'SECONDARY_STORAGE': '/storag
e/sdcard1', 'EMULATED_STORAGE_SOURCE': '/mnt/shell/emulated', 'EMULATED_STORAGE_TARGET': '/storage/emulated', 'ANDROID_PROPERTY_WORKSPACE': '9,0', 'ANDROID_SOCKET_zygot
e': '10', 'ANDROID_ENTRYPOINT': 'main.pyc', 'ANDROID_ARGUMENT': '/data/data/org.test.web/files/app', 'ANDROID_APP_PATH': '/data/data/org.test.web/files/app', 'ANDROID_P
RIVATE': '/data/data/org.test.web/files', 'ANDROID_UNPACK': '/data/data/org.test.web/files/app', 'PYTHONHOME': '/data/data/org.test.web/files/app', 'PYTHONPATH': '/data
/data/org.test.web/files/app:/data/data/org.test.web/files/app/lib', 'PYTHONOPTIMIZE': '2', 'P4A_BOOTSTRAP': 'SDL2', 'PYTHON_NAME': 'python', 'P4A_IS_WINDOWED': 'True',
'P4A_ORIENTATION': 'portrait', 'P4A_NUMERIC_VERSION': 'None', 'P4A_MINSDK': '21', 'LC_CTYPE': 'C.UTF-8'})
I/python  ( 5223): Android kivy bootstrap done. __name__ is __main__
I/python  ( 5223): AND: Ran string
I/python  ( 5223): Run user program, change dir and execute entrypoint
I/python  ( 5223): [INFO   ] [Logger      ] Record log in /data/data/org.test.web/files/app/.kivy/logs/kivy_20-09-05_1.txt
I/python  ( 5223): [INFO   ] [Kivy        ] v1.11.1
I/python  ( 5223): [INFO   ] [Kivy        ] Installed at "/data/data/org.test.web/files/app/_python_bundle/site-packages/kivy/__init__.pyc"
I/python  ( 5223): [INFO   ] [Python      ] v3.7.5 (default, Sep  4 2020, 21:10:56)  
I/python  ( 5223): [Clang 8.0.2 (https://android.googlesource.com/toolchain/clang 40173bab62ec7462
I/python  ( 5223): [INFO   ] [Python      ] Interpreter at "android_python"
I/python  ( 5223): [INFO   ] [Factory     ] 184 symbols loaded
I/python  ( 5223): [INFO   ] [Image       ] Providers: img_tex, img_dds, img_sdl2, img_gif (img_pil, img_ffpyplayer ignored)
I/python  ( 5223): [INFO   ] [Window      ] Provider: sdl2
I/python  ( 5223): [INFO   ] [GL          ] Using the "OpenGL ES 2" graphics system
I/python  ( 5223): [INFO   ] [GL          ] Backend used <sdl2>
I/python  ( 5223): [INFO   ] [GL          ] OpenGL version <b'OpenGL ES 2.0'>
I/python  ( 5223): [INFO   ] [GL          ] OpenGL vendor <b'ARM'>
I/python  ( 5223): [INFO   ] [GL          ] OpenGL renderer <b'Mali-400 MP'>
I/python  ( 5223): [INFO   ] [GL          ] OpenGL parsed version: 2, 0
I/python  ( 5223): [INFO   ] [GL          ] Texture max size <4096>
I/python  ( 5223): [INFO   ] [GL          ] Texture max units <8>
I/python  ( 5223): [INFO   ] [Window      ] auto add sdl2 input provider
I/python  ( 5223): [INFO   ] [Window      ] virtual keyboard not allowed, single mode, not docked
I/python  ( 5223): [WARNING] [Base        ] Unknown <android> provider
I/python  ( 5223): [INFO   ] [Base        ] Start application main loop
I/python  ( 5223): [INFO   ] [Base        ] Leaving application in progress...
I/python  ( 5223):  Traceback (most recent call last):
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/app/main.py", line 39, in <module>
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/platform/build-armeabi-v7a/build/python-installs/web/kivy/app.py", line 855, in run
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/platform/build-armeabi-v7a/build/python-installs/web/kivy/base.py", line 504, in runTouchApp
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/platform/build-armeabi-v7a/build/python-installs/web/kivy/core/window/window_sdl2.py", line 747, in main
loop
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/platform/build-armeabi-v7a/build/python-installs/web/kivy/core/window/window_sdl2.py", line 479, in _mai
nloop
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/platform/build-armeabi-v7a/build/python-installs/web/kivy/base.py", line 339, in idle
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/platform/build-armeabi-v7a/build/python-installs/web/kivy/clock.py", line 591, in tick
I/python  ( 5223):    File "kivy/_clock.pyx", line 384, in kivy._clock.CyClockBase._process_events
I/python  ( 5223):    File "kivy/_clock.pyx", line 414, in kivy._clock.CyClockBase._process_events
I/python  ( 5223):    File "kivy/_clock.pyx", line 412, in kivy._clock.CyClockBase._process_events
I/python  ( 5223):    File "kivy/_clock.pyx", line 154, in kivy._clock.ClockEvent.tick
I/python  ( 5223):    File "kivy/_clock.pyx", line 88, in kivy._clock.ClockEvent.get_callback
I/python  ( 5223):    File "/home/sahil/app2/.buildozer/android/platform/build-armeabi-v7a/build/python-installs/web/kivy/weakmethod.py", line 47, in __call__
I/python  ( 5223):  AttributeError: 'Wv' object has no attribute 'f2'
I/python  ( 5223): Python for android ended.

[Robert Flatt]

Lots of posts about weakmethod here, set kivy==2.0.0rc3  and do a 'buildozer appclean' before the next build.

I don't know if the 'f2' is the same issue, if it is not I have no suggestion for that.

[Degenerate Tech]

done from this link...now it is working 

https://github.com/kivy/python-for-android/issues/1908 

@run_on_ui_thread
def create_webview(*args):
	webview = WebView(activity)
	webview.getSettings().setJavaScriptEnabled(True)
	wvc = WebViewClient();
	webview.setWebViewClient(wvc);
	activity.setContentView(webview)
	webview.loadUrl('https://google.com')

please tell me meaning of @run_on_ui_thread ....

[Degenerate Tech]

but how to implement android  back button to go previous page in webview ?