Flutter Secure Storage not working after build in release mode

Question

Everything works fine in debug mode and release on emulator, but reading values from FlutterSecureStorage fails on a physical device. Other functionalities in application work properly, when I comment using FlutterSecureStorage.

After installing .apk file and launching application on a device, it uses FlutterSecureStorage to get information if user is logged in or not, along with other values. I expect null during first run, of course, but storage.read(key) seams to fail before returning any value.

Added backup tags in main/AndroidManifest.xml

Added deleting keys on startup

final FlutterSecureStorage storage = FlutterSecureStorage();

Future checkIfUserIsSignedIn() async {
    storage.deleteAll();

    try{
      isUserSignedIn = await storage.read(key: _isLoggedIn);
    }
    catch (e){
      print(e);
    }
    setState(() {});
  }

Tried with FlutterSecureStorage v.3.3.3 and FlutterSecureStorage v.3.2.0, but there was no change. I checked SDK version of my device (Honor 10) - 29. Also checked on other device (Samsung Galaxy S9+), but the issue also occurs.

Running flutter run --release causes warnings:

Note: Some input files use unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
Note: C:\Users\karo\flutter\.pub-cache\hosted\pub.dartlang.org\flutter_secure_storage-3.2.0\android\src\main\java\com\it_nomads\fluttersecurestorage\FlutterSecureStoragePlugin.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.

and error:

Installing build\app\outputs\flutter-apk\app.apk...                376ms
Error: ADB exited with exit code 1
Performing Streamed Install

adb: failed to install C:\Users\karo\idom_mobile\build\app\outputs\flutter-apk\app.apk: Failure [INSTALL_FAILED_UPDATE_INCOMPATIBLE: Package com.project.idom signatures do not match previously installed version; ignoring!]
Uninstalling old version...
Installing build\app\outputs\flutter-apk\app.apk...                 6.9s

but successfully installs application on emulator and everything works as expected. The problem is when I install application on physical device. To generate .apk I use flutter build apk --release and install using app-release.apk file as stated in build log:

flutter build apk --release
You are building a fat APK that includes binaries for android-arm, android-arm64, android-x64.
If you are deploying the app to the Play Store, it's recommended to use app bundles or split the APK to reduce the APK size.
    To generate an app bundle, run:
        flutter build appbundle --target-platform android-arm,android-arm64,android-x64
        Learn more on: https://developer.android.com/guide/app-bundle
    To split the APKs per ABI, run:
        flutter build apk --target-platform android-arm,android-arm64,android-x64 --split-per-abi
        Learn more on:  https://developer.android.com/studio/build/configure-apk-splits#configure-abi-split
Running Gradle task 'assembleRelease'...
Running Gradle task 'assembleRelease'... Done                      69.9s
√ Built build\app\outputs\flutter-apk\app-release.apk (48.9MB).

My flutter doctor -v

flutter doctor -v
[√] Flutter (Channel dev, 1.24.0-10.2.pre, on Microsoft Windows [Version 10.0.18362.1198], locale en-GB)
    • Flutter version 1.24.0-10.2.pre at C:\Users\karo\flutter
    • Framework revision 022b333a08 (27 hours ago), 2020-11-18 11:35:09 -0800
    • Engine revision 07c1eed46b
    • Dart version 2.12.0 (build 2.12.0-29.10.beta)

[√] Android toolchain - develop for Android devices (Android SDK version 30.0.2)
    • Android SDK at C:\Users\karo\AppData\Local\Android\sdk
    • Platform android-30, build-tools 30.0.2
    • Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
    • Java version OpenJDK Runtime Environment (build 1.8.0_242-release-1644-b01)
    • All Android licenses accepted.

[√] Android Studio (version 4.1.0)
    • 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 1.8.0_242-release-1644-b01)

[√] Connected device (1 available)
    • Android SDK built for x86 64 (mobile) • emulator-5554 • android-x64 • Android 10 (API 29) (emulator)

• No issues found!

I tried to make sure my project is migrated to AndroidX and got a message: No Usages Found in the Project.

I don't have any more ideas, could you help me?

EDIT

I tried using SharedPreferences as a temporary workaround, but it still didn't work - as I guess, the package was not initialized.

I built my app with flutter build apk --release --no-shrink after reading this thread https://github.com/flutter/flutter/issues/65334.

Then tried flutter build apk --release --no-shrink with the version of my application that uses FlutterSecureStorage and it worked.

Should I really consider it as a valid fix and always build my application this way?

user_2497859 · Answer

How are you initializing the package? The issue seems to occur while the app runs in the background, A workaround posted in this thread is by registering the plugins on Android's MainActivity - this adds FlutterSecureStoragePlugin.

class MainActivity: FlutterActivity() {
  override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
    GeneratedPluginRegistrant.registerWith(flutterEngine)
  }
}

user_9248506 · Answer

You can fix this like I did

Check in pubspec.yml

environment:
  sdk: ">=2.16.2 <3.0.0"

and

flutter_secure_storage: ^4.2.1

Check in android/app/build.gradle

compileSdkVersion 32

user_17478946 · Answer

did you add the permission to your manifest file?

Flutter Secure Storage not working after build in release mode

3 Answers