Crashlytics fatal is reported as "(anonymous namespace)::ExceptionObjHolderImpl" instead of Kotlin exception on iOS

[redelg]

Summary

On iOS, unhandled Kotlin crashes are reported in Firebase Crashlytics as:

Fatal Exception: (anonymous namespace)::ExceptionObjHolderImpl

instead of showing the Kotlin exception as the main fatal cause.

Environment

• Device: iPhone 16 Pro Max
• iOS: 26.2.1
• Kotlin: 2.3.10
• Compose Multiplatform: 1.9.3
• Firebase iOS SDK (SPM): 12.9.0
• NSExceptionKt Crashlytics reporter (SPM)
• nsexception-kt-core: 1.0.7

Configuration

FirebaseApp.configure()
NSExceptionKt.addReporter(.crashlytics(causedByStrategy: .append))

Steps to Reproduce

1. Launch the iOS app.
2. Trigger a Kotlin test crash from the app UI.
3. Wait for the crash to appear in Firebase Crashlytics.
4. Open the crash event details.

Expected Result

Crashlytics fatal should identify the Kotlin exception origin/class as the main crash cause.

Actual Result

Crashlytics fatal is still reported as:

Fatal Exception: (anonymous namespace)::ExceptionObjHolderImpl

Kotlin frames and Kotlin stacktrace logs are present, but the fatal classification remains generic.

Stack Trace (excerpt)

Fatal Exception: (anonymous namespace)::ExceptionObjHolderImpl
Crashed: com.google.firebase.crashlytics.ios.exception
...
FIRCLSExceptionRecordNSException
CrashlyticsNSExceptionKtReporter.reportException(_:)
kfun:com.rickclephas.kmp.nsexceptionkt.core.addReporter...
kfun:com.rickclephas.kmp.nsexceptionkt.core.wrapUnhandledExceptionHook...
kfun:androidx.compose.ui.scene.BaseComposeScene#sendPointerEvent...

[rickclephas]

Hey! I am unable to reproduce this. Could you possibly provide a reproducer for this?

[kormateusz]

I have the same issue, my stack:

• Device: iPhone 12
• iOS: 26.2.1
• Kotlin: 2.3.0
• Compose Multiplatform: 1.10.0
• Firebase iOS SDK: 12.12.0
• NSExceptionKt Crashlytics reporter (SPM)
• nsexception-kt-core: 1.0.6
• Koin: 4.1.1
• Navigation Compose: 2.9.1

Pseudocode of my app structure:

@Composable
fun App() {
      NavHost() {
            val viewModel = koinViewModel<SomeViewModel>()
            SomeScreen(viewModel)
      }
}

@Composable
fun SomeScreen(viewModel: SomeViewModel) {
      throw Exception("Booom!")  <------ Here is OK
      Button(
           onClick = {
                throw Exception("Booom!")  <------(anonymous namespace)::ExceptionObjHolderImpl
                viewModel.foo()
           }
      )
}

@Composable
class SomeViewModel() {
      fun foo() {
           throw Exception("Booom!")  <------ (anonymous namespace)::ExceptionObjHolderImpl
      }
}

[RemyLivewall]

We are seeing similar results in an app we have with functions that are in Composables or inlined in handlers

[rickclephas]

FYI this looks like an initialisation issue, see KT-86576 for more details.