Hi Nazmi,
When the ironSource SDK the following error is being thrown:
E/GeneratedPluginRegistrant: Error registering plugin ironsource_ads, com.ironsource.ironsource_ads.IronsourcePlugin java.lang.IllegalStateException: registrar.activity() must not be null
There is might be an issue with registering the plugin with the FlutterEngine. Please try fixing it from this point.
As we don't officially support Flutter there is not much we can assist. If you will have any questions we will try to assist.
Andrii
Technical Solutions Engineer