Firebase-android-sdk: Crash in Android 8 and 9 after applying dexguard

[AyatKhraisat]

• Android Studio version: Android Studio 3.6.1
• Firebase Component: Firebase-messaging
• Component version: 19.0.1

Crash in Android 8 and 9 in the background when sending push notification through firebase after applying dexguard obfuscation, same issue happen after updating the Firebase to 20.10

android.content.res.Resources$NotFoundException: String resource ID #0x0
        at android.content.res.Resources.getText(Resources.java:363)
        at android.content.res.Resources.getString(Resources.java:456)
        at android.content.Context.getString(Context.java:580)
        at o.hc.ɩ(SourceFile:243)
        at o.he.ι(SourceFile:5007)
        at o.gW.ι(SourceFile:59)
        at o.fC.run(SourceFile:3002)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1167)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:641)
        at o.ɬі.run(Unknown Source:6)
        at java.lang.Thread.run(Thread.java:764)

our firebase Messaging Service Implementation:
`public class ShahidFirebaseMessagingService extends FirebaseMessagingService {

private static final String TAG = ShahidFirebaseMessagingService.class.getSimpleName();
public static final String KEY_URL = "url";

@Override
public void onNewToken(String registrationToken) {
    super.onNewToken(registrationToken);
    if (BuildConfig.DEBUG) {
        Log.d("TOKEN", "--->> " + registrationToken);
    }
}

@Override
public void onMessageReceived(RemoteMessage remoteMessage) {

    // Check Remote Message
    if (remoteMessage == null) {
        Log.e(TAG, "RemoteMessage is null");
        return;
    }

    // Check Notification In RemoteMessage
    if (remoteMessage.getNotification() == null) {
        Log.e(TAG, "Notification is null");
        return;
    }
    String messageId = remoteMessage.getMessageId();
    RemoteMessage.Notification remoteMessageNotification = remoteMessage.getNotification();
    String title = remoteMessageNotification.getTitle();
    String content = remoteMessageNotification.getBody();
    if (TextUtils.isEmpty(content)) {
        Log.e(TAG, "Notification message content is null or empty");
        return;
    }
    Context context = getApplicationContext();
    Map<String, String> customDataMap = remoteMessage.getData();
    String deepLinkUrl = null;
    if (customDataMap != null && customDataMap.containsKey(KEY_URL)) {
        deepLinkUrl = customDataMap.get(KEY_URL);
    }
    Notification localNotification = NotificationHandler.getInstance(context).buildNotification(R.mipmap.ic_launcher, title, content, deepLinkUrl);
    // Using hash code since notification id is String by default
    NotificationHandler.getInstance(context).notify(Math.abs(messageId.hashCode()), localNotification);

}

}`

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[TizioIncognito]

I found the problem.
Firebase load a string with name and not with R.string....
int var5 = var0.getResources().getIdentifier("fcm_fallback_notification_channel_label", "string", var0.getPackageName());
Then Dexguard remove this string.

With these two lines in the dexguard configuration you specify to keep the string above and all the strings that start with "fcm_"
-keepresources string/fcm_fallback_notification_channel_label
-keepresources string/fcm_*

[AyatKhraisat]

@TizioIncognito it's working Thank you!, but I think it should be handled inside the Firebase library so I will keep the issue open

[luangs7]

Any plans to put this solution inside the library?

[matpag]

Same problem for me with DexGuard.
Thank you @TizioIncognito for the temporary workaround

[ashwinraghav]

Thanks for reporting.
Unfortunately, this is not a use case we can support since dexguard is not part of the default android toolchain unlike proguard.
Please report back if there are issues with proguard though.