Why are my Android push notifications working in debug mode but not in the release build?

This usually comes from a configuration difference between your debug and release builds — most often the package name (the applicationId in build.gradle).

Firebase Cloud Messaging delivers to a specific, unique package name. If your release build produces a package name that is not registered in your Firebase project, the device registration will fail and notifications will not be delivered.

How to troubleshoot and fix

1. Inspect your build.gradle. Check whether the buildTypes block sets a different applicationId or adds an applicationIdSuffix for one of the build types:

   android {
     defaultConfig {
       applicationId "com.yourcompany.yourapp"
     }
     buildTypes {
       debug {
         // This suffix changes the final package name for debug builds
         applicationIdSuffix ".debug"
       }
       release {
         // The package name for release builds stays "com.yourcompany.yourapp"
       }
     }
   }

2. Verify the Firebase registration. In Firebase Console → Project settings → Your apps, make sure an Android app is registered with the package name your release build produces (for example com.yourcompany.yourapp). If you use build-type-specific package names, each one needs its own Android app entry in Firebase.
3. Check google-services.json. Download the file again after adding/changing the package name and place it in android/app/. The package_name value inside it must match your release applicationId.
4. Check the Pushwoosh platform configuration. Pushwoosh does not store the Android package name. Android is configured with an FCM v1 service account key: go to Settings → Configure platforms, click Connect in the Android row and upload the JSON private key generated in Firebase Console → Project settings → Service accounts. Make sure this key belongs to the same Firebase project in which your release package name is registered.
5. Perform a clean installation. Fully uninstall the app from the test device, then install the release build. This forces a fresh device registration with the correct settings.

Legacy FCM Server Key / Sender ID credentials were discontinued by Google in June 2024 and are no longer used anywhere in Pushwoosh or in the Pushwoosh Android SDK.