Module with the Main dispatcher is missing with version 1.3.0-RC2 and other versions as well

[elPoyoLoco]

This crash has been haunting me occasionally for a few months now:

Fatal Exception: java.lang.IllegalStateException: Module with the Main dispatcher is missing. Add dependency providing the Main dispatcher, e.g. 'kotlinx-coroutines-android'
at kotlinx.coroutines.internal.MissingMainCoroutineDispatcher.missing + 90(MissingMainCoroutineDispatcher.java:90)
at kotlinx.coroutines.internal.MissingMainCoroutineDispatcher.isDispatchNeeded + 71(MissingMainCoroutineDispatcher.java:71)
at kotlinx.coroutines.DispatchedKt.resumeCancellable + 420(DispatchedKt.java:420)
at kotlinx.coroutines.intrinsics.CancellableKt.startCoroutineCancellable + 26(CancellableKt.java:26)
at kotlinx.coroutines.CoroutineStart.invoke + 109(CoroutineStart.java:109)
at kotlinx.coroutines.AbstractCoroutine.start + 154(AbstractCoroutine.java:154)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch + 54(BuildersKt__Builders_commonKt.java:54)
at kotlinx.coroutines.BuildersKt.launch + 1(BuildersKt.java:1)
at kotlinx.coroutines.BuildersKt__Builders_commonKt.launch$default + 47(BuildersKt__Builders_commonKt.java:47)
at kotlinx.coroutines.BuildersKt.launch$default + 1(BuildersKt.java:1)
at com.example.user.ui.screens.mapScreen.MapActivity$getLocation$1.onChanged + 667(MapActivity.java:667)
at com.example.user.ui.screens.mapScreen.MapActivity$getLocation$1.onChanged + 46(MapActivity.java:46)
at androidx.lifecycle.LiveData.considerNotify + 131(LiveData.java:131)
at androidx.lifecycle.LiveData.dispatchingValue + 149(LiveData.java:149)
at androidx.lifecycle.LiveData.setValue + 307(LiveData.java:307)
at androidx.lifecycle.MutableLiveData.setValue + 50(MutableLiveData.java:50)
at androidx.lifecycle.Transformations$1.onChanged + 76(Transformations.java:76)
at androidx.lifecycle.MediatorLiveData$Source.onChanged + 152(MediatorLiveData.java:152)
at androidx.lifecycle.LiveData.considerNotify + 131(LiveData.java:131)
at androidx.lifecycle.LiveData.dispatchingValue + 149(LiveData.java:149)
at androidx.lifecycle.LiveData.setValue + 307(LiveData.java:307)
at androidx.lifecycle.MutableLiveData.setValue + 50(MutableLiveData.java:50)
at com.example.user.domain.repository.location.LocationRepository.submitLocation + 95(LocationRepository.java:95)
at com.example.user.domain.repository.location.LocationRepository.access$submitLocation + 18(LocationRepository.java:18)
at com.example.user.domain.repository.location.LocationRepository$getLocation$callback$1.onLocationResult + 59(LocationRepository.java:59)
at com.google.android.gms.internal.location.zzau.notifyListener + 4(zzau.java:4)
at com.google.android.gms.common.api.internal.ListenerHolder.notifyListenerInternal + 17(ListenerHolder.java:17)
at com.google.android.gms.common.api.internal.ListenerHolder$zaa.handleMessage + 5(ListenerHolder.java:5)
at android.os.Handler.dispatchMessage + 106(Handler.java:106)
at com.google.android.gms.internal.base.zap.dispatchMessage + 8(zap.java:8)
at android.os.Looper.loop + 214(Looper.java:214)
at android.app.ActivityThread.main + 6981(ActivityThread.java:6981)
at java.lang.reflect.Method.invoke(Method.java)
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run + 493(RuntimeInit.java:493)
at com.android.internal.os.ZygoteInit.main + 1445(ZygoteInit.java:1445)

This is the latest crash with coroutines version kotlinx-coroutines-android:1.3.0-RC2, AS 3.5, Gradle 5.1.1, AGP 3.4.2,
R8 enabled, version 1.4.94.
This particular crash happened on Samsung 9 running android 9, but i have also seen the crash (crashlytics) it on other versions and devices as well:
Redmi 4x with android 7.1.2 and the following properties:
AS 3.4.2, gradle 5.1.1, AGP 3.4.1

and on older versions of coroutines, this time bundled with core:kotlinx-coroutines-android:1.1.1, gradle 5.1.1 and AGP 3.4.1 on pocophone f1 running android 9, samsung j5 running android 8.1.0.

i have been unable to reproduce this issue on any of our production builds. I have also gone through all the issues related to MissingMainCoroutineDispatcher i could find here and on SO, yet none of the solutions seems to work. Some suggested that using -core as well -android might be related, but this happens as well without -core. Other suggested the packaging might get corrupted during when signing the app, but we have used the same build flow before without issues. i have also added the following proguard rules, while fully aware those are not required when using R8:

`# Coroutines

ServiceLoader support

-keepnames class kotlinx.coroutines.internal.MainDispatcherFactory {}
-keepnames class kotlinx.coroutines.CoroutineExceptionHandler {}
-keepnames class kotlinx.coroutines.android.AndroidExceptionPreHandler {}
-keepnames class kotlinx.coroutines.android.AndroidDispatcherFactory {}

Most of volatile fields are updated with AFU and should not be mangled

-keepclassmembernames class kotlinx.** {
volatile ;
}`

Also without any visible effect. I have also seen suggestions regarding the signing process and specifically the final production apk, and the META-INF/services folder - and it looks like this when i open the apk in AS:

So not sure when to go from here and what, and would appreciate any insights you may have on this.

[AChep]

I have got the same crash in logs for Samsung S8 Plus on Android Pie. He got this crash 14 times in a day (and probably uninstalled the app, idk).

I use version 1.2.1 of coroutines

[ispbox]

1.3.0 version works for me on Android, but 1.3.2 has the same error. I use android version of coroutines

"org.jetbrains.kotlinx:kotlinx-coroutines-android:1.3.2"

Nothing helps - only downgrade. The problem exist in debug build as well, so it is not connected with Proguard.

[qwwdfsad]

We will hopefully fix this issue in #1572
It's really hard to pinpoint as it's only reproduced on real devices under unknown circumstances

[elPoyoLoco]

i wasnt able to reproduce it at all on any of our real devices nor emulators, and i am not familiar enough with service loader to be of any help here. the crashes are so sporadic, its about 1 user in 500, and by looking at the apk's i do not see anything problematic.

[elPoyoLoco]

We will hopefully fix this issue in #1572
It's really hard to pinpoint as it's only reproduced on real devices under unknown circumstances

after a few releases that did not stumble into this issue, the problem has resurfaced in our latest deploy. any idea when #1572 will be merged into master?

[qwwdfsad]

Most likely in the next release (1.3.3)

[Neristance]

Hi, any news when 1.3.3 is going to be released with the fix from #1572 ?
Thanks :)

[qwwdfsad]

During this year :)
The only blocker right now is fixing kotlinx-coroutines-test and then release is ready

[professorbk]

This error just happened to my Huawei device.
Resolved by "Rebuild project".
Hope this may help.
I am using Kotlin 1.3.2

[Malachiasz]

A workaround seems to be using: Handler(Looper.getMainLooper()).asCoroutineDispatcher() instead of Dispatchers.Main. IMHO it's a critical bug, because random crashes with stable versions are undermining users trust, that JetBrain delivers stable, reliable libraries. It undermines trust to Kotlin on Android as a mature solution.

[elPoyoLoco]

A workaround seems to be using: Handler(Looper.getMainLooper()).asCoroutineDispatcher() instead of Dispatchers.Main. IMHO it's a critical bug, because random crashes with stable versions are undermining users trust, that JetBrain delivers stable, reliable libraries. It undermines trust to Kotlin on Android as a mature solution.

could not agree more with the "critical bug" part, not just because i am experiencing it, but because it is so random and hard to reproduce. I have actually managed to stumble into it with a debug build, but it went away after an invalidate cache/restart so not much to lean on with that.

Thanks for the workaround, but ill wait for the merge, whenever that might happen.

[qwwdfsad]

Fixed in 1.3.3