Provider kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler not found

[GeoffreyMetais]

We recently pushed VLC on beta, with some Kotlin code.
And we see some users reporting this ClassNotFoundException
Project configuration is:
Kotlin version 1.2.21
Kotlinx version 0.21.2

Identified devices are:
Acer GT-810 (rolex) Android 5.1
OnePlus One (A0001) Android 4.3
Xiaomi Redmi Note 4 (mido) Android 7.0

VLC gradle build files are here and here

Concerned exception handler here.

kotlinx.coroutines.experimental.DispatchException: Unexpected exception running DispatchedContinuation[UI, org.videolan.vlc.gui.DiffUtilAdapter$internalUpdate$2@c13506a]
	at kotlinx.coroutines.experimental.DispatchedTask$DefaultImpls.run(Dispatched.kt:165)
	at kotlinx.coroutines.experimental.DispatchedContinuation.run(Dispatched.kt:25)
	at android.os.Handler.handleCallback(Handler.java:754)
	at android.os.Handler.dispatchMessage(Handler.java:95)
	at android.os.Looper.loop(Looper.java:163)
	at android.app.ActivityThread.main(ActivityThread.java:6237)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:877)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
	at Android.MODEL(Redmi Note 4)
	at Android.VERSION(7.0)
	at Android.FINGERPRINT(xiaomi/mido/mido:7.0/NRD90M/V9.0.5.0.NCFMIEI:user/release-keys)
Caused by: java.util.ServiceConfigurationError: kotlinx.coroutines.experimental.CoroutineExceptionHandler: Provider kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler not found
	at java.util.ServiceLoader.fail(ServiceLoader.java:225)
	at java.util.ServiceLoader.-wrap1(ServiceLoader.java)
	at java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:366)
	at java.util.ServiceLoader$1.next(ServiceLoader.java:448)
	at kotlinx.coroutines.experimental.CoroutineExceptionHandlerKt.handleCoroutineException(CoroutineExceptionHandler.kt:98)
	at kotlinx.coroutines.experimental.StandaloneCoroutine.onCancellation(Builders.kt:185)
	at kotlinx.coroutines.experimental.JobSupport.completeUpdateState$kotlinx_coroutines_core(Job.kt:718)
	at kotlinx.coroutines.experimental.JobSupport.updateState$kotlinx_coroutines_core(Job.kt:659)
	at kotlinx.coroutines.experimental.JobSupport.makeCompletingInternal$4cfcfd05(Job.kt:1051)
	at kotlinx.coroutines.experimental.JobSupport.makeCompletingOnce$kotlinx_coroutines_core$4cfcfd16(Job.kt:1037)
	at kotlinx.coroutines.experimental.AbstractCoroutine.resumeWithException(AbstractCoroutine.kt:48)
	at kotlin.coroutines.experimental.jvm.internal.CoroutineImpl.resume(CoroutineImpl.kt:53)
	at kotlinx.coroutines.experimental.DispatchedTask$DefaultImpls.run(Dispatched.kt:161)
	at kotlinx.coroutines.experimental.DispatchedContinuation.run(Dispatched.kt:25)
	at android.os.Handler.handleCallback(Handler.java:754)
	at android.os.Handler.dispatchMessage(Handler.java:95)
	at android.os.Looper.loop(Looper.java:163)
	at android.app.ActivityThread.main(ActivityThread.java:6237)
	at java.lang.reflect.Method.invoke(Native Method)
	at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:877)
	at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:767)
Caused by: java.lang.ClassNotFoundException: kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler
	at java.lang.Class.classForName(Native Method)
	at java.lang.Class.forName(Class.java:400)
	at java.util.ServiceLoader$LazyIterator.next(ServiceLoader.java:364)
	... 18 more
Caused by: java.lang.ClassNotFoundException: Didn't find class "kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler" on path: DexPathList[[zip file "/data/app/org.videolan.vlc-2/base.apk"],nativeLibraryDirectories=[/data/app/org.videolan.vlc-2/lib/arm64, /data/app/org.videolan.vlc-2/base.apk!/lib/arm64-v8a, /system/lib64, /vendor/lib64]]
	at dalvik.system.BaseDexClassLoader.findClass(BaseDexClassLoader.java:56)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:380)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:312)
	... 21 more

[elizarov]

That seems to a ProGuard issue. kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler seems to have been removed by ProGuard, even though it is references from META-INF/services/kotlinx.coroutines.experimental.CoroutineExceptionHandler and should have been kept. Most likely, it needs to be explicitly configured to "keep". I'm extremely surprised it is not kept by default. It is either ProGuard bug or some project-specific ProGuard configuration that is causing it. Can you share your ProGuard configuration, please?

[JakeWharton]

You explicitly have to add

# The Android pre-handler for exceptions is loaded reflectively (via ServiceLoader).
-keep class kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler { *; }

[GeoffreyMetais]

Thank you!

But it would be systematic if it was the case no?
Here, it only happens on a very few devices with the same app build.

[GeoffreyMetais]

Proguard conf is here https://code.videolan.org/videolan/vlc-android/blob/2.9.0/vlc-android/proguard.cfg

[elizarov]

The reason it is not systematic is that it happens only when some other uncaught exception happens. The app is about the crash, but the code that is supposed to handle that cannot handle the exception, because it cannot find kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler class that should be there. I'm having hard time reproducing it. I cannot figure out how it can be happening.

[elizarov]

I've assembled vlc-android release on my machine and looked into resulting apk and into the dex file inside. Indeed, kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler is not there. I turns out I can reproduce it with a simple project. I see when minifyEnabled true then this class gets removed from the .dex. I still cannot reproduce it under emulator, since I cannot figure out how to deploy my "release" apk there. It seems to be deploying "debug" apk under emulator which does not experience this problem.

[GeoffreyMetais]

Yes, proguard only applies on release builds.

adb install -r app_release.apk ?

[Karthika-Kishore]

Our team is getting recently having this crash.

Caused by java.lang.ArrayStoreException
kotlinx.coroutines.android.AndroidExceptionPreHandler cannot be stored in an array of type qh.b0[]

Adding below lines also doesn't helped.

The Android pre-handler for exceptions is loaded reflectively (via ServiceLoader).

-keep class kotlinx.coroutines.experimental.android.AndroidExceptionPreHandler { *; }

Please let me know is there a way to fix this.

[dkhalanskyjb]

@Karthika-Kishore, please contact Android maintainers or the manufacturer of the device. This looks like a bug in modification facilities.