kotlin.coroutines.jvm.internal.CompletedContinuation cannot be cast to kotlinx.coroutines.internal.DispatchedContinuation

[Mygod]

I am seeing the following error reported by users. I cannot reproduce this personally. What can I do to investigate this error?

Fatal Exception: kotlinx.coroutines.CoroutinesInternalError
Fatal exception in coroutines machinery for AwaitContinuation(DispatchedContinuation[Dispatchers.IO, Continuation at be.mygod.librootkotlinx.RootServer.execute(RootServer.kt:255)@868b2dc]){Completed}@d3b5fe5. Please read KDoc to 'handleFatalException' method and report this incident to maintainers
kotlinx.coroutines.DispatchedTask.handleFatalException (DispatchedTask.java:144)
kotlinx.coroutines.DispatchedTask.run (DispatchedTask.java:115)
kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely (CoroutineScheduler.java:571)
kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask (CoroutineScheduler.java:750)
kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker (CoroutineScheduler.java:678)
kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run (CoroutineScheduler.java:665)
Caused by java.lang.ClassCastException
kotlin.coroutines.jvm.internal.CompletedContinuation cannot be cast to kotlinx.coroutines.internal.DispatchedContinuation
kotlinx.coroutines.CoroutineDispatcher.releaseInterceptedContinuation (CoroutineDispatcher.java:108)
kotlin.coroutines.jvm.internal.ContinuationImpl.releaseIntercepted (ContinuationImpl.java:118)
kotlin.coroutines.jvm.internal.BaseContinuationImpl.resumeWith (BaseContinuationImpl.java:39)
kotlinx.coroutines.DispatchedTask.run (DispatchedTask.java:106)
kotlinx.coroutines.scheduling.CoroutineScheduler.runSafely (CoroutineScheduler.java:571)
kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.executeTask (CoroutineScheduler.java:750)
kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.runWorker (CoroutineScheduler.java:678)
kotlinx.coroutines.scheduling.CoroutineScheduler$Worker.run (CoroutineScheduler.java:665)

Related code: https://github.com/Mygod/VPNHotspot/blob/v2.11.6/mobile/src/main/java/be/mygod/librootkotlinx/RootServer.kt#L255

[Togrias]

Do you or the users happen to use value (inline) classes? Including kotlin 1.5 Result?

[Mygod]

Value class yes but as far as I'm concerned it is not used in this part of the code. Not sure about Result so presumably not.

[Togrias]

I'm encountering similar issues on a multiplatform project. No problems on javascript or native, only jvm causes issues. I suspect a compiler issue.

Update: I refactored Result into my own normal class Result2 and the issue seemed to go away. Seems like I'm right that it's a kotlin compiler issue and not a coroutines issue. Try refactoring value classes into normal classes?

See: https://youtrack.jetbrains.com/issue/KT-45685

[qwwdfsad]

This is indeed a regression in Kotlin 1.5.0, unfortunately, we cannot workaround it on kotlinx.coroutines site.

The root cause of this issue is the compiler trying to optimize any boxing of value classes, but in some places coroutines code generation relies on it (e.g. resumeWith(Result)), so just replacing Result with the same handwritten type resolves the issue