Flutter Release APK crashes with GSON error java.lang.AssertionError: AssertionError (GSON 2.8.5): java.lang.NoSuchFieldException: UNKNOWN E/flutter (14343):

[fritz-playmaker]

Flutter release-apk crashes as soon as I open the app with a GSON error

Error Log

[ERROR:flutter/shell/platform/android/platform_view_android_jni.cc(40)] java.lang.AssertionError: AssertionError (GSON 2.8.5): java.lang.NoSuchFieldException: UNKNOWN
E/flutter (14343): at com.google.a.f.a(Unknown Source)
E/flutter (14343): at com.google.a.f.a(Unknown Source)
E/flutter (14343): at com.google.a.f.a(Unknown Source)
E/flutter (14343): at com.b.a.b.a$a.b(Unknown Source)
E/flutter (14343): at com.b.a.a.onMethodCall(Unknown Source)
E/flutter (14343): at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(Unknown Source)
E/flutter (14343): at io.flutter.view.FlutterNativeView.handlePlatformMessage(Unknown Source)
E/flutter (14343): at android.os.MessageQueue.nativePollOnce(Native Method)
E/flutter (14343): at android.os.MessageQueue.next(MessageQueue.java:143)
E/flutter (14343): at android.os.Looper.loop(Looper.java:130)
E/flutter (14343): at android.app.ActivityThread.main(ActivityThread.java:6117)
E/flutter (14343): at java.lang.reflect.Method.invoke(Native Method)
E/flutter (14343): at java.lang.reflect.Method.invoke(Method.java:372)
E/flutter (14343): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
E/flutter (14343): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
E/flutter (14343): Caused by: java.lang.AssertionError: java.lang.NoSuchFieldException: UNKNOWN
E/flutter (14343): at com.google.a.b.a.n$a.(Unknown Source)
E/flutter (14343): at com.google.a.b.a.n$24.a(Unknown Source)
E/flutter (14343): at com.google.a.f.a(Unknown Source)
E/flutter (14343): at com.google.a.b.a.a$1.a(Unknown Source)
E/flutter (14343): at com.google.a.f.a(Unknown Source)
E/flutter (14343): ... 15 more
E/flutter (14343): Caused by: java.lang.NoSuchFieldException: UNKNOWN
E/flutter (14343): at java.lang.Class.getField(Class.java:1104)
E/flutter (14343): ... 20 more
E/flutter (14343):
F/flutter (14343): [FATAL:flutter/shell/platform/android/platform_view_android_jni.cc(77)] Check failed: CheckException(env).

[JakeWharton]

It's not clear why this is a Gson problem. It looks like obfuscation removed a field. Can you provide a self-contained sample that fails and demonstrates that Gson has a bug?

[fritz-playmaker]

@JakeWharton I honestly do not know the steps to reproduce this error. It popped up whilst installing my release apk in Flutter and it explicitly states java.lang.AssertionError: AssertionError (GSON 2.8.5): so i decided to report it here

[oliverbytes]

I figured the culprit here. It happens when minifyEnabled is set to true. So just disable it and it should fix

I commented these on my app/build.gradle and now works

buildTypes {
        release {
                .........
                minifyEnabled false // set this to false to prevent java.lang.NoSuchFieldException

[burkard]

You saved me a lot of headaches, @nemoryoliver !
Thanks!!

[oliverbytes]

I can feel you @burkard . So happy I've helped. You're welcome

[mohsenoid]

FYI, you are disabling your proguard!! be careful!

[MegatronKing]

Add the below in proguard-rules.pro, it will be fixed!

-keepclassmembers enum * {*;}

[eug48]

I seem to have solved this with flutter build apk --no-shrink ...
My build wasn't using proguard/minifyEnabled, and strangely my APK was crashing on an Android 7 device, but not on an Android 9 device..

[Dorbmon]

Thanks for your help!You exactly saved me.

[cahyowhy]

do we have another alternative to use shrink

[Marcono1234]

Probably same issue as #924

[viroth-ty]

Add these lines of code, fixed for me

buildTypes {
    release {
        minifyEnabled false
        shrinkResources true
        proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
    }
} 

[rajatsangrame]

Add the below in proguard-rules.pro, it will be fixed!

-keepclassmembers enum * {*;}

It worked!