FlutterFragmentActivity support for predictive back

Internal: b/242216228

Use case

Several popular pub packages (local_auth, health) require the use of FlutterFragmentActivity in apps. Apps that use those packages should be able to support predictive back, too.

Proposal

Predictive back support was added to FlutterActivity in flutter-team-archive/engine#52302 and to FlutterFragment in flutter-team-archive/engine#52302. Support should also be added to FlutterFragmentActivity, including support for route transitions (flutter-team-archive/engine#49093).

What is predictive back?

Gif

What are predictive back route transitions?

Video

predictive_back.mp4

I'm experiencing the same issue, and can't add predictive back if i use local auth in my projects

The package flutter_stripe also requires FlutterFragmentActivity. So I'm stuck with Flutter v3.22.3. Our project is totally crappy without back gesture since the "Stable" version of Flutter v3.24.1. 😥
I understand that you must be very busy, but do you have an ETA for an update? 😅

@NeKoFu

If I try to just change FlutterActivity to FlutterFragmentActivity in MainActivity.kt it seems to be working, am I missing something? Predictive back works when leaving the app from the root route. PredictiveBackPageTransition doesn't work, but it correctly defaults to ZoomPageTransition and back gestures work.

class MainActivity: FlutterFragmentActivity() {
}

@NeKoFu what is your setup like? Can you try on the master branch?

Maybe I did enable this in FlutterFragmentActivity here? https://github.com/flutter/engine/pull/52302/files#diff-893547c230a70f1b0618f0b79a56c67d8506f0983a5a92b819f13c1071fd7d84

Example app that I used, just navigation nothing fancy

import 'package:flutter/material.dart';

void main() async {
  runApp(const _MyApp());
}

class _MyApp extends StatelessWidget {
  const _MyApp();

  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      restorationScopeId: 'root',
      theme: ThemeData(
        pageTransitionsTheme: const PageTransitionsTheme(
          builders: {
            TargetPlatform.android: PredictiveBackPageTransitionsBuilder(),
          },
        ),
      ),
      title: 'Flutter Demo',
      initialRoute: '/',
      routes: <String, WidgetBuilder>{
        '/': (BuildContext context) {
          return const MyHomePage();
        },
        'leaf': (BuildContext context) {
          return const LeafPage();
        },
      },
    );
  }
}

class MyHomePage extends StatelessWidget {
  const MyHomePage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            ElevatedButton(
              child: const Text('Open next page'),
              onPressed: () => Navigator.of(context).restorablePushNamed('leaf'),
            ),
          ],
        ),
      ),
    );
  }
}

class LeafPage extends StatelessWidget {
  const LeafPage({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.center,
        children: [
          ElevatedButton(
            child: const Text('Open modal'),
            onPressed: () => showModalBottomSheet<void>(
              context: context,
              useRootNavigator: true,
              builder: (context) => const Padding(
                padding: EdgeInsets.all(24),
                child: Text(
                  'Close this modal and then use system back nav, '
                  'which will unexpectedly close the app.',
                ),
              ),
            ),
          ),
          const SizedBox(height: 16, width: double.infinity),
          ElevatedButton(
            child: const Text('Open dialog'),
            onPressed: () => showDialog<void>(
              context: context,
              useRootNavigator: true,
              builder: (context) => const AlertDialog(
                contentPadding: EdgeInsets.all(24),
                content: Text(
                  'Close this dialog and then use system back nav, '
                  'which will unexpectedly close the app.',
                ),
              ),
            ),
          ),
        ],
      ),
    );
  }
}

@justinmc

@justinmc I'm using go_router for navigation, and since the flutter_stripe package requires FlutterFragmentActivity, I had to switch to that. With Flutter 3.22.3, the back gesture worked as expected, returning to the previous page. However, after upgrading to Flutter 3.24.1 (stable channel), the back gesture now closes the app instead of navigating back.

I will try with the master branch tomorrow 😉

@justinmc

@justinmc To isolate the issue, I had created, like you, a minimal project with navigation between two pages using go_router. And indeed, good news, this minimal project is working again using the master branch and your commits related to FlutterFragmentActivity. 😊

However, 😥 I was still facing the problem on my actual application project. So, I took some time to investigate, and what I found is that if a function is attached to the onNavigationNotification attribute in MaterialApp.router(), then the Back Gesture consistently closes the application. 🤔

import 'package:flutter/material.dart';
import 'package:navtest/route.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp.router(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
        useMaterial3: true,
      ),
      routerConfig: AppRoutes.router,
      // onNavigationNotification: (NavigationNotification notification) => true, // <<-- break the fix and close the app on back gesture
    );
  }
}

@darshankawar

@darshankawar @justinmc Any chance this can be bumped to P1? Entire app navigation seems to be really broken in many ways for apps using FlutterFragmentActivity (which is also unavoidable for many projects) and disabling predictive back on android manifest doesn't seem to fix it anymore starting with flutter 3.24. Both PopScope and the old WillPopScope don't work as intended at all.

Thanks for everyone providing context here. I'm trying to find the bandwidth for this and will post back. If anyone else wants to submit a PR, I'll assign myself if I start working on this, otherwise it's free for anyone to work on it.

For anyone having the same issue, this workaround fixes navigation the navigation for Flutter 3.24.x : Milad-Akarie/auto_route_library#2059 (comment)

sample project to reproduce the issue https://github.com/safaIocod/iso_sample

Steps to reproduce
1- Run the project
2- Switch the tab using the bottom navigation bar
3- go to the inner page
4 - press the back button (will redirect to the home page),
5 - press the back button once more (the app will close)

expected result
As per the code , on the step 5 app should go to the 1st tab in the bottom navigation bar , again pressing back button from there should show a confirmation dialogue

@AlexDochioiu

For anyone having the same issue, this workaround fixes navigation the navigation for Flutter 3.24.x : Milad-Akarie/auto_route_library#2059 (comment)

Hi @AlexDochioiu, after i trying your reference but still not working for me. I try routing using https://docs.flutter.dev/cookbook/navigation/named-routes not working, and i try using other way https://pub.dev/packages/go_router still not working to using system navigation back for pop route.

flutter doctor:

[√] Flutter (Channel stable, 3.24.4, on Microsoft Windows [Version 10.0.26100.2454], locale en-US)
    • Flutter version 3.24.4 on channel stable at C:\Flutter\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 603104015d (5 weeks ago), 2024-10-24 08:01:25 -0700
    • Engine revision db49896cf2
    • Dart version 3.5.4
    • DevTools version 2.37.3

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    • Android SDK at C:\Users\***\AppData\Local\Android\sdk
    • Platform android-35, build-tools 35.0.0
    • Java binary at: C:\Users\***\.jdks\corretto-17.0.13\bin\java
    • Java version OpenJDK Runtime Environment Corretto-17.0.13.11.1 (build 17.0.13+11-LTS)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.11.5)
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
    • Visual Studio Community 2022 version 17.11.35327.3
    • Windows 10 SDK version 10.0.22621.0

[√] Android Studio (version 2024.2)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 21.0.3+-12282718-b509.11)

[√] IntelliJ IDEA Community Edition (version 2024.2)
    • IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2024.2.4
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart

[√] VS Code (version 1.95.3)
    • VS Code at C:\Users\***\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.100.0

[√] Connected device (4 available)
    • sdk gphone64 x86 64 (mobile) • emulator-5554 • android-x64    • Android 15 (API 35) (emulator)
    • Windows (desktop)            • windows       • windows-x64    • Microsoft Windows [Version 10.0.26100.2454]
    • Chrome (web)                 • chrome        • web-javascript • Google Chrome 131.0.6778.86
    • Edge (web)                   • edge          • web-javascript • Microsoft Edge 130.0.2849.80

[√] Network resources
    • All expected network resources are available.

• No issues found!

@AlexDochioiu

For anyone having the same issue, this workaround fixes navigation the navigation for Flutter 3.24.x : Milad-Akarie/auto_route_library#2059 (comment)

Hi @AlexDochioiu, after i trying your reference but still not working for me. I try routing using https://docs.flutter.dev/cookbook/navigation/named-routes not working, and i try using other way https://pub.dev/packages/go_router still not working to using system navigation back for pop route.

flutter doctor:

[√] Flutter (Channel stable, 3.24.4, on Microsoft Windows [Version 10.0.26100.2454], locale en-US)
    • Flutter version 3.24.4 on channel stable at C:\Flutter\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 603104015d (5 weeks ago), 2024-10-24 08:01:25 -0700
    • Engine revision db49896cf2
    • Dart version 3.5.4
    • DevTools version 2.37.3

[√] Windows Version (Installed version of Windows is version 10 or higher)

[√] Android toolchain - develop for Android devices (Android SDK version 35.0.0)
    • Android SDK at C:\Users\***\AppData\Local\Android\sdk
    • Platform android-35, build-tools 35.0.0
    • Java binary at: C:\Users\***\.jdks\corretto-17.0.13\bin\java
    • Java version OpenJDK Runtime Environment Corretto-17.0.13.11.1 (build 17.0.13+11-LTS)
    • All Android licenses accepted.

[√] Chrome - develop for the web
    • Chrome at C:\Program Files\Google\Chrome\Application\chrome.exe

[√] Visual Studio - develop Windows apps (Visual Studio Community 2022 17.11.5)
    • Visual Studio at C:\Program Files\Microsoft Visual Studio\2022\Community
    • Visual Studio Community 2022 version 17.11.35327.3
    • Windows 10 SDK version 10.0.22621.0

[√] Android Studio (version 2024.2)
    • Android Studio at C:\Program Files\Android\Android Studio
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart
    • Java version OpenJDK Runtime Environment (build 21.0.3+-12282718-b509.11)

[√] IntelliJ IDEA Community Edition (version 2024.2)
    • IntelliJ at C:\Program Files\JetBrains\IntelliJ IDEA Community Edition 2024.2.4
    • Flutter plugin can be installed from:
       https://plugins.jetbrains.com/plugin/9212-flutter
    • Dart plugin can be installed from:
       https://plugins.jetbrains.com/plugin/6351-dart

[√] VS Code (version 1.95.3)
    • VS Code at C:\Users\***\AppData\Local\Programs\Microsoft VS Code
    • Flutter extension version 3.100.0

[√] Connected device (4 available)
    • sdk gphone64 x86 64 (mobile) • emulator-5554 • android-x64    • Android 15 (API 35) (emulator)
    • Windows (desktop)            • windows       • windows-x64    • Microsoft Windows [Version 10.0.26100.2454]
    • Chrome (web)                 • chrome        • web-javascript • Google Chrome 131.0.6778.86
    • Edge (web)                   • edge          • web-javascript • Microsoft Edge 130.0.2849.80

[√] Network resources
    • All expected network resources are available.

• No issues found!

Did you use the Getx as route manager?

@ZhuJHua

Hi @ZhuJHua, sorry but I don't use Getx...do you have any ideas? I have to use FlutterFragmentActivity for local_auth, but after changing from FlutterActivity i have a problem cannot back (using system back button) to previous page and app will minimize after click system back button. I think you have same problem but unlucky i cannot fixing with this solution (Milad-Akarie/auto_route_library#2059 (comment)) to my project.

Any updates on this? Proper support for FlutterFragmentActivity is very important since important features like biometrics login cannot work without it.

Any updates on this?

I am not entirely sure, if I do completly understand this issue. However the problems previously experienced with back button handling in a FlutterFragementActivity after upgrading to Flutter 3.22 seem to be resolved with the release of Flutter 3.32 (probably by #161545).

I am not entirely sure, if I do completly understand this issue. However the problems previously experienced with back button handling in a FlutterFragementActivity after upgrading to Flutter 3.22 seem to be resolved with the release of Flutter 3.32 (probably by #161545).

I'm using auto_route, predictive back gesture on my main screen well work using3.32 but not the others (created by .push). Does your routes works ?

I am not entirely sure, if I do completly understand this issue. However the problems previously experienced with back button handling in a FlutterFragementActivity after upgrading to Flutter 3.22 seem to be resolved with the release of Flutter 3.32 (probably by #161545).

This remains an issue as of Flutter 3.35.7.

It works when exiting the app, but internal page transitions are not using Predictive Back. Unfortunately libraries like RevenueCat require FlutterFragementActivity, so I cannot switch.

Has anyone found a workaround for this?

I use this approach. Navigation seems fine with it

final materialApp = MaterialApp(
      // FLUTTER 3.24.x and newer (when using FlutterFragmentActivity)
      // android navigation bugs due to predictive back gesture
      // https://github.com/flutter/flutter/issues/149753
      // https://github.com/Milad-Akarie/auto_route_library/issues/1788
      // https://github.com/flutter/flutter/issues/145290
      // https://github.com/flutter/flutter/issues/138614#issuecomment-1909155402
      // https://github.com/flutter/flutter/issues/145159
      // https://github.com/flutter/flutter/issues/138737
      // https://github.com/flutter/flutter/issues/155441
      //
      // Note, we cannot get rid of FlutterFragmentActivity because it is required for local auth to work
      onNavigationNotification: UniversalPlatform.isAndroid
          ? (notification) {
              switch (WidgetsBinding.instance.lifecycleState) {
                case null:
                case AppLifecycleState.detached:
                case AppLifecycleState.inactive:
                  // Avoid updating the engine when the app isn't ready.
                  return true;
                case AppLifecycleState.resumed:
                case AppLifecycleState.hidden:
                case AppLifecycleState.paused:
                  SystemNavigator.setFrameworkHandlesBack(true);

                  /// This must be `true` instead of `notification.canHandlePop`, otherwise application closes on back gesture.
                  return true;
              }
            }
          : null,

I use this approach. Navigation seems fine with it

Thanks for this, but this did not work for me.

Are there any other steps that you had to apply to get this to work (aside from the pageTransitionsTheme and AndroidManifest code changes).

To confirm it wasn't something else in my config preventing it, I just switched back to FlutterActivity and predictive back worked.

(Just to clarify, I am talking about predictive back within the app, where you can see the previous screen mid-gesture.)

@anders-au

@anders-au Those changes are meant to properly disable predictive gestures (I think also in android manifest you'd need to do it) because it breaks app navigation in flutter.

To my knowledge, you cannot possibly use predictive gestures with FlutterFragementActivity without breaking the navigation.

Your only choice are:

Use FlutterFragementActivity and fully disable predictive gestures
Use FlutterActivity to be able to keep predictive gestures, but ofc this is not possible with some libraries.

I never found any workaround to use FlutterFragementActivity with predictive gestures.

[Android] Add predictive back support for FlutterFragment and Flutter…

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.

[Android] Add predictive back support for FlutterFragment and Flutter…

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FlutterFragmentActivity support for predictive back #149753

Use case

Proposal

What is predictive back?

What are predictive back route transitions?

4 remaining items

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FlutterFragmentActivity support for predictive back #149753

Description

Use case

Proposal

What is predictive back?

What are predictive back route transitions?

Activity

roberto-gigli commented on Jun 7, 2024

NeKoFu commented on Sep 3, 2024

justinmc commented on Sep 3, 2024

NeKoFu commented on Sep 4, 2024

NeKoFu commented on Sep 8, 2024

AlexDochioiu commented on Oct 20, 2024

justinmc commented on Oct 22, 2024

AlexDochioiu commented on Oct 29, 2024

bazl-E commented on Nov 5, 2024

backids99 commented on Dec 1, 2024

ZhuJHua commented on Dec 1, 2024

backids99 commented on Dec 1, 2024

4 remaining items

AlexDochioiu commented on Jan 10, 2025

kevinhuijsman13 commented on Jan 16, 2025

FrankenApps commented on May 25, 2025

EArminjon commented on May 25, 2025

anders-au commented on Nov 6, 2025

AlexDochioiu commented on Nov 6, 2025

anders-au commented on Nov 7, 2025

AlexDochioiu commented on Nov 7, 2025

github-actions commented on Feb 16, 2026

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