I m confused by how to properly use CoroutineExceptionHandle

Question

I m confused by how to properly use CoroutineExceptionHandler I tried ``` import kotlinx coroutines CoroutineExceptionHandler import kotlinx coroutines coroutineScope import kotlinx coroutines launch import kotlinx coroutines runBlocking import kotlin system exitProcess fun main = runBlocking val handler = CoroutineExceptionHandler t gt println handling exception $t exitProcess 1 coroutineScope launch handler println running throw Exception OMG Unit ``` I would expect this to print handling exception and exit the process Instead it shows that an exception was unhandled in `main` I ll paste in the thread

David Glasser · Answer

``` running Exception in thread main java lang Exception OMG at mdg engine selfmonitoring TmpKt$main$1$1$1 invokeSuspend tmp kt 17 at kotlin coroutines jvm internal BaseContinuationImpl resumeWith ContinuationImpl kt 33 at kotlinx coroutines DispatchedTask run Dispatched kt 241 at kotlinx coroutines EventLoopImplBase processNextEvent EventLoop common kt 270 at kotlinx coroutines BlockingCoroutine joinBlocking Builders kt 79 at kotlinx coroutines BuildersKt BuildersKt runBlocking Builders kt 54 at kotlinx coroutines BuildersKt runBlocking Unknown Source at kotlinx coroutines BuildersKt BuildersKt runBlocking$default Builders kt 36 at kotlinx coroutines BuildersKt runBlocking$default Unknown Source at mdg engine selfmonitoring TmpKt main tmp kt 9 at mdg engine selfmonitoring TmpKt main tmp kt ```

David Glasser · Answer

Oh hmm Maybe this is related to gt This also a reason why in these examples CoroutineExceptionHandler is always installed to a coroutine that is created in GlobalScope It does not make sense to install an exception handler to a coroutine that is launched in the scope of the main runBlocking since the main coroutine is going to be always cancelled when its child completes with exception despite the installed handler at <https kotlinlang org docs reference coroutines exception handling html>

gildor · Answer

Exception handler doesn t make sense for such use case in general particularry it doesn t work here because you use coroutineScope isntead of supervisorScope

David Glasser · Answer

indeed try catch was fine