async {
    try {
        async { throw IOException() }.await()
    } catch (e: IOException) {
    }
}

I get no Exception.

If the parent is an

async

it is the same, but exception is not logged, because you're supposed to call

await

Just favor suspending function and you'll be fine

Here's some reading you may find interesting: https://github.com/Kotlin/kotlinx.coroutines/issues/753 https://github.com/Kotlin/kotlinx.coroutines/issues/763

One need

async

only for parallel decomposition. For other uses-cases just use suspending functions (without using

async

at all)