Missing classes detected while running R8

[Zeinab-Kouhkan]

ERROR: Missing classes detected while running R8. Please add the missing classes or apply additional keep rules that are generated in ...\build\app\outputs\mapping\websiteRelease\missing_rules.txt.
ERROR: R8: Missing class ir.metrix.flutter.Reflection (referenced from: void ir.metrix.flutter.Metrix.onMethodCall(io.flutter.plugin.common.MethodCall, io.flutter.plugin.common.MethodChannel$Result))

[Zeinab-Kouhkan]

Workaround / Fix

1. Create a ProGuard rules file
   In your Flutter project’s Android module, create (or open) android/app/proguard-rules.pro.

2. Add keep-rules
   Paste the following into android/app/proguard-rules.pro:

   # Keep the Reflection helper class
   -keep class ir.metrix.flutter.Reflection { *; }
   
   # Keep the class invoked via reflection
   -keep class ir.metrix.notification.MetrixNotification { *; }
   
   # Keep its static loadInAppMessages() method
   -keepclassmembers class ir.metrix.notification.MetrixNotification {
       public static void loadInAppMessages();
   }
   
   # Suppress warnings about missing Reflection
   -dontwarn ir.metrix.flutter.Reflection
   
   

3.Update your Gradle config
Open android/app/build.gradle and inside the
android { buildTypes { release { … } } } block ensure you include:

release {
  minifyEnabled true
  shrinkResources true
  proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'),
                'proguard-rules.pro'}

4.Rebuild

flutter clean
flutter pub get
flutter build apk --release