Flutterfire: [firebase_messaging] getToken() fails to return an FCM token, blocks forever in await

[kroikie]

Note: This issue could be Android specific, I didn't test it on iOS yet.

The behavior of firebaseMessaging.getToken() is mysterious.

I am facing a problem where firebaseMessaging.getToken() no longer returns anything, thus await firebaseMessaging.getToken() will block forever. I'm quite sure that the code worked before. I tried to figure out why, but no luck so far - the code behaves differently on Java and Flutter side.

Here's the details.

There's nothing special on the initialization of firebaseMessaging, I'm posting it here anyway:

  final FirebaseMessaging firebaseMessaging = new FirebaseMessaging();
  firebaseMessaging.configure(onMessage: (Map<String, dynamic> message) async {
    print('OnMessage');
    print(message);
  }, onLaunch: (Map<String, dynamic> message) {
    print('onLaunch()');
  }, onResume: (Map<String, dynamic> message) {
    print('onResume()');
  });

   firebaseMessaging.requestNotificationPermissions();

The problem is at the firebaseMessaging.getToken() call, which never returns a token and blocks forever:

String fcmToken = await firebaseMessaging.getToken();

This had happened before, but was kind of "resolved" by moving the above line later at my app's init stage. Today it happened again, and I decided to try to figure out the cause.

So I opened the Java project, added the following code (copied from the Firebase's example), had it called from Flutter through platform channel, to see if I could see a more verbose error output by retrieving the token manually (bypassing the firebaseMessaging plugin).

...
if (call.method.equals("getFCMToken")) {
  FirebaseInstanceId.getInstance().getInstanceId()
      .addOnCompleteListener(new OnCompleteListener<InstanceIdResult>() {
        @Override
        public void onComplete(@NonNull Task<InstanceIdResult> task) {
          if (!task.isSuccessful()) {
            Log.w(TAG, "getInstanceId failed", task.getException());
            return;
          }

          // Get new Instance ID token
          String token = task.getResult().getToken();

          // Log and toast
          String msg = "Token: "+ token;
          Log.d(TAG, msg);
          Toast.makeText(MainActivity.this, msg, Toast.LENGTH_SHORT).show();
        }
      });
}
...

In Flutter, I added this getFCMToken() call BEFORE firebaseMessaging.getToken(). To my surprise, this getFCMToken() finishes almost immediately with an FCM token, no error! But the subsequent firebaseMessaging.getToken() still blocks forever!

So I set some breakpoints in the java files of the firebase messaging plugin, and found that broadcastToken() was not called at all. This is strange.

Not knowing what happened, I uninstalled the app and run it again (still on the Java side). This time broadcastToken() is called, which is invoked from this line! As a matter of course, firebaseMessaging.getToken() returns the FCM token successfully.

Then I switched to the Flutter side and run my project again hoping to see the issue "fixed" and boom! getFCMToken() succeeded but firebaseMessaging.getToken() still failed!

Then I went back to the Java side, hoping that it would fail again so that I would know why the code under the "configure" method call isn't running. Unfortunately, the code in Java side worked correctly!

Then I went back to the Flutter side, ran flutter clean, and rerun the code. Still fails on firebaseMessaging.getToken().

Now I am in a situation where the same code is acting differently when compiled in "Flutter mode" and "Android mode". I feel really frustrated because it seems impossible to track the cause of the issue.

[√] Flutter (Channel dev, v0.5.7, on Microsoft Windows [Version 10.0.17134.165], locale zh-HK)
    • Flutter version 0.5.7 at C:\flutter
    • Framework revision 66091f9696 (4 weeks ago), 2018-07-09 12:52:41 -0700
    • Engine revision 6fe748490d
    • Dart version 2.0.0-dev.63.0.flutter-4c9689c1d2

[√] Android toolchain - develop for Android devices (Android SDK 27.0.3)
    • Android SDK at C:\Users\CY\AppData\Local\Android\sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-27, build-tools 27.0.3
    • Java binary at: C:\Program Files\Android\Android Studio 3\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b02)
    • All Android licenses accepted.

[!] Android Studio (version 3.0)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin version 22.2.1
    • Dart plugin version 171.4424
    X Unable to determine bundled Java version.
    • Try updating or re-installing Android Studio.

[√] Android Studio (version 3.1)
    • Android Studio at C:\Program Files\Android\Android Studio 3
    • Flutter plugin version 27.1.1
    • Dart plugin version 173.4700
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1024-b02)

[!] Android Studio (version 2.1)
    • Android Studio at C:\Android\android-studio
    X Flutter plugin not installed; this adds Flutter specific functionality.
    X Dart plugin not installed; this adds Dart specific functionality.
    X Unable to find bundled Java version.
    • Try updating or re-installing Android Studio.

[!] VS Code, 64-bit edition (version 1.23.0)
    • VS Code at C:\Program Files\Microsoft VS Code
    • Flutter extension not installed; install from
      https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[√] Connected devices (1 available)
    • Nexus 5X • 00e1c63e154fae10 • android-arm64 • Android 8.1.0 (API 27)

! Doctor found issues in 3 categories.

---

Addendum: To temporary work around this issue, I modified my platform channel code as follow, and have it called before firebaseMessaging.getToken().

...
if (call.method.equals("getFCMToken")) {
    FlutterFirebaseInstanceIDService.broadcastToken(MainActivity.this);
}
...

This seems to overcome the issue that broadcastToken isn't called from the plugin code. But of course this can't be a solution. Also not tested on iOS.

[carolhs]

Hi, Just curious if you have figured a way to resolve this issue in Flutter when using firebaseMessaging.getToken(). I saw this issue has been closed, but could not find a demonstrated solution. thx

[kroikie]

@carolhs this may have been closed in error during the transfer of the issue. Thanks for calling this out.

[wezzle]

I can confirm this sometimes occurs on iOS (13) as well. I can not really find out what is causing it to sometimes occur. The problem seems to be timing related. I do a call to that function in multiple locations in the app but only the one called on startup sometimes blocks forever.

[SebastienMelki]

Hey everyone,
Did anyone figure out a solution for this? My getToken() hangs forever, and if I put a timeout on it, it just returns null.

I am unable to get an FCM token on iOS physical device.

Someone got this to work?
Thanks

[alexbrinkman]

I also have the issue. It works fine on Android in an emulator, but not on the iOS simulator.

[alexbrinkman]

All - I finally found a solution to my version of this issue. Within my Google cloud account, I had to add the Firebase Installations API restriction to the key that my app was using to connect to Google Cloud. I noticed that there were 100% errors calling that api in the Google cloud logs dashboard. Then when adding that restriction and giving it time to resolve, my token started to show. I know many of you are having intermittent issues, which seems to be a different problem. But if you are just getting a null token, perhaps this will help.

[abin-saju]

All - I finally found a solution to my version of this issue. Within my Google cloud account, I had to add the Firebase Installations API restriction to the key that my app was using to connect to Google Cloud. I noticed that there were 100% errors calling that api in the Google cloud logs dashboard. Then when adding that restriction and giving it time to resolve, my token started to show. I know many of you are having intermittent issues, which seems to be a different problem. But if you are just getting a null token, perhaps this will help.

Thanks! This pointed me in the right direction. After setting up messaging I couldn't get token on iOS, turns out its because the above api was failing. I simply added Firebase Installations API to api key autogenerated by firebase (and referenced in GoogleService-Info.plist file )

[Unown-Fashion]

@abin-saju Could you please tell what exactly did you pasted in .plist file?

[abin-saju]

@abin-saju Could you please tell what exactly did you pasted in .plist file?

@Unown-Fashion I didn't add anything to the .plist. You simply need to find the api key in the .plist and look for it in console.cloud.google.com and add 'Firebase Installation API' to API restrictions.

[Unown-Fashion]

@abin-saju
Thanks a lot for explanation!
Now I've restricted that, but getToken() still hangs for some reason...

[Salakar]

Hey all 👋

As part of our roadmap (#2582) we've just shipped a complete rework of the firebase_messaging plugin that aims to solve this and many other issues.

If you can, please try out the dev release (see the migration guide for upgrading and for changes) and if you have any feedback then join in the discussion here.

Given the scope of the rework I'm going to go ahead and close this issue in favor of trying out the latest plugin.

Thanks everyone 🤓

[bionara]

I still can't get this working (it just hangs and never yields a token) on iOS - device or sim. Works fine on android. Any updates?

[neon97]

Looking for the solution the function to get the firebase token gets stuck... anyone whoever has got the solution it works fine on android ....any suggestions would be appreciated.