IronSource Adapter status "Failed: Not Found" on Android 9

[MayisGM]

[REQUIRED] Step 1: Describe your environment

Unity version: 2022.3.62f3

Google Mobile Ads Unity plugin version: v11.0.0

Plugin installation method: .unitypackage import

Platform: Android

Platform OS version: Android 9 (API 28) — Note: Works perfectly on Android 14 (API 34)

Any specific devices issue occurs on: Any device running Android 9 / API 28

Mediation ad networks used, and their versions: IronSourceUnityAdapter v4.5.1, AppLovinUnityAdapter v8.7.3, LiftoffMonetizeUnityAdapter v5.7.3, MetaAudienceNetworkUnityAdapter v3.18.5, UnityAdsUnityAdapter v3.17.0

[REQUIRED] Step 2: Describe the problem

Steps to reproduce:

Integrate Google Mobile Ads Unity plugin v11.0.0 along with IronSourceUnityAdapter v4.5.1 into a Unity 2022.3 project.

Build the project for Android and run it on a device with Android 9 (API 28).

Open Ad Inspector to check mediation adapter statuses.

Observe that while all other adapters initialize correctly, IronSource fails with: Adapter: Failed: Not Found and SDK: Failed: Not Ready.

Checking adb logcat reveals a NoClassDefFoundError due to a missing android.window.OnBackInvokedCallback class, which was introduced in Android 13 (API 33) and does not exist in Android 9. This causes the runtime to reject the entire ControllerActivity class initialization.

Logcat Output

Rejecting re-init on previously-failed class java.lang.Class<com.ironsource.sdk.controller.ControllerActivity$$ExternalSyntheticLambda0>: java.lang.NoClassDefFoundError: Failed resolution of: Landroid/window/OnBackInvokedCallback;
at java.lang.Class com.ironsource.adqualitysdk.sdk.i.kk.É(java.lang.String, boolean) (:22)
at java.lang.Class com.ironsource.adqualitysdk.sdk.i.be.ç(java.lang.String, boolean) (:134)

[MayisGM]

The same issue exists in the previous IronSource Unity Adapter 4.5.0 version. Downgrading to the adapter version 4.4.1 solved the issue, so the problem appeared starting from the adapter 4.5.0 version.

[vinkini]

Seems like an issue with the IronSource SDK. As correctly pointed out, this was only added in API 33. We will try to escalate this and get it on their radar.