io.flutter.embedding.engine.dart.DartMessenger$Reply.reply

[Chhukdy]

🐛 Bug Report

Type: java.lang.IllegalStateException

Exception java.lang.IllegalStateException: Reply already submitted
at io.flutter.embedding.engine.dart.DartMessenger$Reply.reply (DartMessenger.java:431)
at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler$1.success (MethodChannel.java:272)
at com.tundralabs.fluttertts.FlutterTtsPlugin.onInitListenerWithCallback$lambda$3 (FlutterTtsPlugin.java:241)
at android.speech.tts.TextToSpeech.lambda$dispatchOnInit$0$android-speech-tts-TextToSpeech (TextToSpeech.java:890)
at android.speech.tts.TextToSpeech$$ExternalSyntheticLambda1.run (Unknown Source:4)
at android.speech.tts.TextToSpeech.dispatchOnInit (TextToSpeech.java:899)
at android.speech.tts.TextToSpeech.-$$Nest$mdispatchOnInit (Unknown Source)
at android.speech.tts.TextToSpeech$Connection$SetupConnectionAsyncTask.onPostExecute (TextToSpeech.java:2280)
at android.speech.tts.TextToSpeech$Connection$SetupConnectionAsyncTask.onPostExecute (TextToSpeech.java:2240)
at android.os.AsyncTask.finish (AsyncTask.java:771)
at android.os.AsyncTask.-$$Nest$mfinish (Unknown Source)
at android.os.AsyncTask$InternalHandler.handleMessage (AsyncTask.java:788)
at android.os.Handler.dispatchMessage (Handler.java:106)
at android.os.Looper.loopOnce (Looper.java:226)
at android.os.Looper.loop (Looper.java:313)
at android.app.ActivityThread.main (ActivityThread.java:8762)
at java.lang.reflect.Method.invoke
at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run (RuntimeInit.java:604)
at com.android.internal.os.ZygoteInit.main (ZygoteInit.java:1067)

Version: 4.2.3

Platform:

• 🤖 Android
• :[Samsung Galaxy A12][Android 13 (SDK 33)] (affected 4 users)

[Chhukdy]

Summary The application experienced a crash due to an IllegalStateException with the message "Reply already submitted." This type of error indicates that an attempt was made to send a response back to the Flutter (Dart) side of the application via a MethodChannel, but a response had already been delivered for that specific method call. The crash originates within the com.tundralabs.fluttertts.FlutterTtsPlugin during its handling of the onInit callback from the Android TextToSpeech engine. This suggests that the plugin's code invoked result.success() (or result.error()) more than once for the same Flutter method invocation that initiated the Text-to-Speech initialization process.

Potential Solutions

Implement a check to prevent multiple replies within the onInit callback. The most direct cause of a "Reply already submitted" error is calling result.success(), result.error(), or result.notImplemented() more than once for a single MethodChannel.Result object. In the FlutterTtsPlugin.onInitListenerWithCallback$lambda$3 method, which is the OnInitListener for TextToSpeech, a mechanism should be introduced to ensure that a reply is sent only once. This can be achieved by using a boolean flag or by nullifying the MethodChannel.Result instance after its initial use.

Conceptual example within the OnInitListener implementation:

// Assuming 'result' is the MethodChannel.Result object captured by the lambda
// and 'replySent' is a volatile boolean flag or managed with synchronization
if (!replySent) {
if (status == TextToSpeech.SUCCESS) {
result.success(true); // Or an appropriate success value
} else {
result.error("TTS_INIT_FAILED", "TextToSpeech initialization failed with status: " + status, null);
}
replySent = true;
} else {
// Log a warning if a subsequent onInit call is received after a reply was sent
android.util.Log.w("FlutterTtsPlugin", "onInit callback received after reply was already sent.");
}
Ensure the MethodChannel.Result object is managed for single use across asynchronous operations. Beyond the immediate onInit callback, the FlutterTtsPlugin might have multiple asynchronous paths that could potentially attempt to send a reply for the same Flutter method call. For example, if a timeout occurs before onInit is invoked, an error might be reported, and then onInit could arrive later, leading to a second reply. The MethodChannel.Result object should be treated as a single-use token. Once success(), error(), or notImplemented() has been invoked, the Result object should be considered consumed, and any subsequent attempts to use it for replying should be prevented, perhaps by setting its reference to null.

Conceptual example showing nullification after use:

// Assuming 'pendingResult' is a class member holding the MethodChannel.Result
// This would be called by the Flutter method handler
public void onMethodCall(@nonnull MethodCall call, @nonnull MethodChannel.Result result) {
if ("initializeTts".equals(call.method)) {
this.pendingResult = result;
// ... initiate TextToSpeech with an OnInitListener that uses pendingResult ...
}
}

// Inside the OnInitListener (equivalent to FlutterTtsPlugin.java:241)
public void onInit(int status) {
if (pendingResult == null) {
android.util.Log.w("FlutterTtsPlugin", "OnInit callback received but no pending result to reply to.");
return;
}
try {
if (status == TextToSpeech.SUCCESS) {
pendingResult.success(true);
} else {
pendingResult.error("TTS_INIT_FAILED", "TextToSpeech initialization failed.", null);
}
} finally {
pendingResult = null; // Clear the result reference after it has been used
}
}